feat: support Python 3.10

[tswast]

• Add constraints files to check minimum versions.
• Syncs noxfile with Google templates.

[tswast]

0.4.1 was the last version to support Python 2.7 from what I can tell. A bit odd that 0.4.2 was a patch release. googleapis/google-auth-library-python-oauthlib#93

[tswast]

Tests pass locally:

(dev-3.10) ➜  pydata-google-auth git:(issue50-core-upgrade) ✗ nox -r
nox > Running session unit-2.7
nox > Re-using existing virtual environment at .nox/unit-2-7.
nox > python -m pip install mock pyfakefs pytest pytest-cov -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-2.7.txt
nox > python -m pip install -e . -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-2.7.txt
nox > py.test --quiet --junitxml=unit_2.7_sponge_log.xml --cov=pydata_google_auth --cov=tests/unit --cov-append --cov-config=.coveragerc --cov-report= --cov-fail-under=0 tests/unit
...............                                                                                               [100%]Coverage.py warning: Couldn't parse Python file '/Users/swast/src/github.com/pydata/pydata-google-auth/pydata_google_auth/__main__.py' (couldnt-parse)

--------- generated xml file: /Users/swast/src/github.com/pydata/pydata-google-auth/unit_2.7_sponge_log.xml ---------


15 passed in 0.83 seconds
nox > Session unit-2.7 was successful.
nox > Running session unit-3.6
nox > Re-using existing virtual environment at .nox/unit-3-6.
nox > python -m pip install mock pyfakefs pytest pytest-cov -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.6.txt
nox > python -m pip install -e . -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.6.txt
nox > py.test --quiet --junitxml=unit_3.6_sponge_log.xml --cov=pydata_google_auth --cov=tests/unit --cov-append --cov-config=.coveragerc --cov-report= --cov-fail-under=0 tests/unit
...............                                                                                               [100%]
--------- generated xml file: /Users/swast/src/github.com/pydata/pydata-google-auth/unit_3.6_sponge_log.xml ---------


15 passed in 0.69s
nox > Session unit-3.6 was successful.
nox > Running session unit-3.7
nox > Re-using existing virtual environment at .nox/unit-3-7.
nox > python -m pip install mock pyfakefs pytest pytest-cov -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.7.txt
nox > python -m pip install -e . -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.7.txt
nox > py.test --quiet --junitxml=unit_3.7_sponge_log.xml --cov=pydata_google_auth --cov=tests/unit --cov-append --cov-config=.coveragerc --cov-report= --cov-fail-under=0 tests/unit
...............                                                                                               [100%]
--------- generated xml file: /Users/swast/src/github.com/pydata/pydata-google-auth/unit_3.7_sponge_log.xml ---------


15 passed in 0.64s
nox > Session unit-3.7 was successful.
nox > Running session unit-3.8
nox > Re-using existing virtual environment at .nox/unit-3-8.
nox > python -m pip install mock pyfakefs pytest pytest-cov -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.8.txt
nox > python -m pip install -e . -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.8.txt
nox > py.test --quiet --junitxml=unit_3.8_sponge_log.xml --cov=pydata_google_auth --cov=tests/unit --cov-append --cov-config=.coveragerc --cov-report= --cov-fail-under=0 tests/unit
...............                                                                                               [100%]
--------- generated xml file: /Users/swast/src/github.com/pydata/pydata-google-auth/unit_3.8_sponge_log.xml ---------


15 passed in 0.62s
nox > Session unit-3.8 was successful.
nox > Running session unit-3.9
nox > Re-using existing virtual environment at .nox/unit-3-9.
nox > python -m pip install mock pyfakefs pytest pytest-cov -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.9.txt
nox > python -m pip install -e . -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.9.txt
nox > py.test --quiet --junitxml=unit_3.9_sponge_log.xml --cov=pydata_google_auth --cov=tests/unit --cov-append --cov-config=.coveragerc --cov-report= --cov-fail-under=0 tests/unit
...............                                                                                               [100%]
--------- generated xml file: /Users/swast/src/github.com/pydata/pydata-google-auth/unit_3.9_sponge_log.xml ---------


15 passed in 0.70s
nox > Session unit-3.9 was successful.
nox > Running session unit-3.10
nox > Re-using existing virtual environment at .nox/unit-3-10.
nox > python -m pip install mock pyfakefs pytest pytest-cov -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.10.txt
nox > python -m pip install -e . -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.10.txt
nox > py.test --quiet --junitxml=unit_3.10_sponge_log.xml --cov=pydata_google_auth --cov=tests/unit --cov-append --cov-config=.coveragerc --cov-report= --cov-fail-under=0 tests/unit
...............                                                                                               [100%]
-------- generated xml file: /Users/swast/src/github.com/pydata/pydata-google-auth/unit_3.10_sponge_log.xml ---------


15 passed in 0.71s
nox > Session unit-3.10 was successful.
nox > Running session system-2.7
nox > Re-using existing virtual environment at .nox/system-2-7.
nox > python -m pip install --pre grpcio
nox > python -m pip install mock pyfakefs pytest pytest-cov google-cloud-testutils -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-2.7.txt
nox > python -m pip install -e . -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-2.7.txt
nox > py.test --quiet --junitxml=system_2.7_sponge_log.xml --cov=pydata_google_auth --cov=tests/system --cov-append --cov-config=.coveragerc --cov-report= --cov-fail-under=0 tests/system
.....                                                                                                         [100%]Coverage.py warning: Couldn't parse Python file '/Users/swast/src/github.com/pydata/pydata-google-auth/pydata_google_auth/__main__.py' (couldnt-parse)

-------- generated xml file: /Users/swast/src/github.com/pydata/pydata-google-auth/system_2.7_sponge_log.xml --------


5 passed in 134.29 seconds
nox > Session system-2.7 was successful.
nox > Running session system-3.8
nox > Re-using existing virtual environment at .nox/system-3-8.
nox > python -m pip install --pre grpcio
nox > python -m pip install mock pyfakefs pytest pytest-cov google-cloud-testutils -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.8.txt
nox > python -m pip install -e . -c /Users/swast/src/github.com/pydata/pydata-google-auth/testing/constraints-3.8.txt
nox > py.test --quiet --junitxml=system_3.8_sponge_log.xml --cov=pydata_google_auth --cov=tests/system --cov-append --cov-config=.coveragerc --cov-report= --cov-fail-under=0 tests/system
.....                                                                                                         [100%]
-------- generated xml file: /Users/swast/src/github.com/pydata/pydata-google-auth/system_3.8_sponge_log.xml --------


5 passed in 9.81s
nox > Session system-3.8 was successful.
nox > Running session cover
nox > Re-using existing virtual environment at .nox/cover.
nox > python -m pip install coverage pytest-cov
nox > coverage report --show-missing --fail-under=68
Name                               Stmts   Miss  Cover   Missing
----------------------------------------------------------------
pydata_google_auth/__init__.py        10      0   100%
pydata_google_auth/__main__.py        35     35     0%   3-103
pydata_google_auth/_version.py       279    152    46%   87-98, 103-106, 117-138, 148-167, 174, 187, 189-223, 242, 246-248, 267, 271, 296-297, 302-309, 320-322, 336, 358-360, 370-377, 390-404, 415-426, 437-446, 458-466, 472, 481, 485-496, 529-530, 541-550
pydata_google_auth/_webserver.py      26      0   100%
pydata_google_auth/auth.py            73     13    82%   96, 113, 149-154, 234, 266-268, 275-276, 354-361, 404
pydata_google_auth/cache.py           91     15    84%   55-57, 103-106, 123-124, 145-151, 231
pydata_google_auth/exceptions.py       2      0   100%
tests/system/__init__.py               0      0   100%
tests/system/test_auth.py             29      0   100%
tests/unit/__init__.py                 0      0   100%
tests/unit/test_auth.py               51      0   100%
tests/unit/test_cache.py              43      1    98%   27
tests/unit/test_webserver.py          43      0   100%
----------------------------------------------------------------
TOTAL                                682    216    68%
nox > coverage erase
nox > Session cover was successful.
nox > Running session lint
nox > Re-using existing virtual environment at .nox/lint.
nox > python -m pip install flake8 black==19.10b0
nox > black --check docs pydata_google_auth tests noxfile.py setup.py
All done! ✨ 🍰 ✨
17 files would be left unchanged.
nox > flake8 pydata_google_auth tests
nox > Session lint was successful.
nox > Running session lint_setup_py
nox > Re-using existing virtual environment at .nox/lint_setup_py.
nox > python -m pip install docutils pygments
nox > python setup.py check --restructuredtext --strict
running check
nox > Session lint_setup_py was successful.
nox > Running session blacken
nox > Re-using existing virtual environment at .nox/blacken.
nox > python -m pip install black==19.10b0
nox > black docs pydata_google_auth tests noxfile.py setup.py
All done! ✨ 🍰 ✨
17 files left unchanged.
nox > Session blacken was successful.
nox > Running session docs
nox > Re-using existing virtual environment at .nox/docs.
nox > python -m pip install sphinx sphinx_rtd_theme ipython
nox > python -m pip install -e .
nox > sphinx-build -W -T -N -b html -d docs/source/_build/doctrees/ docs/source/ docs/source/_build/html/
Running Sphinx v4.0.1
making output directory... done
[autosummary] generating autosummary for: api.rst, changelog.rst, cli.rst, contributing.rst, index.rst, install.rst, intro.rst, privacy.rst
loading intersphinx inventory from https://docs.python.org/objects.inv...
loading intersphinx inventory from https://google-auth.readthedocs.io/en/latest/objects.inv...
loading intersphinx inventory from https://google-auth-oauthlib.readthedocs.io/en/latest/objects.inv...
intersphinx inventory has moved: https://docs.python.org/objects.inv -> https://docs.python.org/3/objects.inv
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 8 source files that are out of date
updating environment: [new config] 8 added, 0 changed, 0 removed
reading sources... [ 12%] api
reading sources... [ 25%] changelog
reading sources... [ 37%] cli
reading sources... [ 50%] contributing
reading sources... [ 62%] index
reading sources... [ 75%] install
reading sources... [ 87%] intro
reading sources... [100%] privacy

looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents... done
writing output... [ 12%] api
writing output... [ 25%] changelog
writing output... [ 37%] cli
writing output... [ 50%] contributing
writing output... [ 62%] index
writing output... [ 75%] install
writing output... [ 87%] intro
writing output... [100%] privacy

generating indices... genindex py-modindex done
writing additional pages... search done
copying static files... done
copying extra files... done
dumping search index in English (code: en)... done
dumping object inventory... done
build succeeded.

The HTML pages are in docs/source/_build/html.
nox > Session docs was successful.
nox > Ran multiple sessions:
nox > * unit-2.7: success
nox > * unit-3.6: success
nox > * unit-3.7: success
nox > * unit-3.8: success
nox > * unit-3.9: success
nox > * unit-3.10: success
nox > * system-2.7: success
nox > * system-3.8: success
nox > * cover: success
nox > * lint: success
nox > * lint_setup_py: success
nox > * blacken: success
nox > * docs: success

[tswast]

3.10 failure is because image needs an update. Mailed TheKevJames/tools#315