*: Centralize requirements.txt and unify dependency versions (#9759)

* python_test: fix cython_examples in doc/ and tests/

* update setup.py to parse the bazel version string better

* all: centralize all python deps into stackable requirements files in python/

* format

* Move cython test into the proper package

* Add cross-reference dependency comments for requirements and setup.py

* re-enable version pinning on CI, fix formatting

* fix up torchvision version

* fix case in shell

python/requirements.txt

@@ -0,0 +1,65 @@
+# These are mirrored in setup.py as install_requires,
+# which is what the users of the ray package will install. The rest of this file
+# sets up all the packages necessary for a /developer/ of Ray.
+#
+# In short, if you change it here, PLEASE also change it in setup.py.
+#
+# setup.py install_requires
+aiohttp
+aioredis
+click >= 7.0
+colorama
+colorful
+filelock
+google
+gpustat
+grpcio >= 1.28.1
+jsonschema
+msgpack >= 1.0.0, < 2.0.0
+numpy >= 1.16
+opencensus
+prometheus_client >= 0.7.1
+protobuf >= 3.8.0
+py-spy >= 0.2.0
+pyyaml
+redis >= 3.3.2, < 3.5.0
+requests
+
+## setup.py extras
+atari_py
+dm_tree
+flask
+gym[atari]
+lz4
+opencv-python-headless
+pandas==1.0.5
+scipy==1.4.1
+tabulate
+tensorboardX
+uvicorn
+
+# Requirements for running tests
+blist; platform_system != "Windows"
+boto3
+cython==0.29.0
+dataclasses
+feather-format
+gym
+kubernetes
+lxml
+mypy
+networkx
+numba
+openpyxl
+pettingzoo
+Pillow; platform_system != "Windows"
+pygments
+pytest==5.4.3
+pytest-asyncio
+pytest-rerunfailures
+pytest-sugar
+pytest-timeout
+scikit-learn==0.22.2
+tensorflow
+werkzeug
+xlrd