[Python docs] Create another requirement file to generated API refere…

…nce documentation

requirements.bazel.txt

@@ -1,4 +1,5 @@
 # GRPC Python setup requirements
+# The requirements listed below are solely for Bazel tests and should not be used elsewhere.
 absl-py==1.4.0
 cachetools==5.3.2
 certifi==2023.7.22

requirements.docs.txt

@@ -0,0 +1,41 @@
+# GRPC Python setup requirements
+# The requirements listed below are used to generated API reference documentation.
+absl-py==1.4.0
+cachetools==5.3.2
+certifi==2023.7.22
+chardet==3.0.4
+charset-normalizer==3.3.2
+coverage==4.5.4
+cython==3.0.0
+Deprecated==1.2.14
+gevent==22.08.0
+google-api-core==2.24.0
+google-auth==2.23.4
+google-cloud-monitoring==2.26.0
+google-cloud-trace==1.15.0
+googleapis-common-protos==1.63.1
+greenlet==1.1.3.post0
+idna==2.7
+importlib-metadata==6.11.0
+oauth2client==4.1.0
+opencensus-context==0.1.3
+opentelemetry-api==1.25.0
+opentelemetry-exporter-prometheus==0.46b0
+opentelemetry-resourcedetector-gcp==1.6.0a0
+opentelemetry-sdk==1.25.0
+opentelemetry-semantic-conventions==0.46b0
+prometheus_client==0.20.0
+proto-plus==1.25.0
+protobuf>=5.27.1,<6.0dev
+pyasn1-modules==0.3.0
+pyasn1==0.5.0
+requests==2.25.1
+rsa==4.9
+setuptools==44.1.1
+typing-extensions==4.9.0
+urllib3==1.26.18
+wheel==0.38.1
+wrapt==1.16.0
+zipp==3.17.0
+zope.event==4.5.0
+zope.interface==6.1

tools/distrib/docgen/_generate_python_doc.sh

@@ -23,7 +23,7 @@ set -ex
 HOME="$(mktemp -d)"
 export HOME
 
-pip install -r requirements.bazel.txt
+pip install -r requirements.docs.txt
 tools/run_tests/run_tests.py -c opt -l python --compiler python3.8 --newline_on_success -j 8 --build_only
 # shellcheck disable=SC1091
 source py38/bin/activate