Merge pull request #40 from CZ-NIC/freeze-lxml

Freeze lxml version to fix tests

setup.py

@@ -17,7 +17,7 @@
       zip_safe=False,
       include_package_data=True,
       install_requires=['zeep @ git+https://github.com/tpazderka/python-zeep.git@signed_parts',
-                        'xmlsec'],
+                        'xmlsec', 'lxml ~= 4.9.3'],
       extras_require={'quality': ['isort', 'flake8', 'pydocstyle', 'mypy'],
                       'tests': ['responses'],
                       'types': ['types-requests']})