ban raw tensorflow imports

.pre-commit-config.yaml

                 .*_pb2.py|
                 .*_pb2_grpc.py
             )$
+        additional_dependencies: [flake8-tidy-imports]
 # "Local" hooks, see https://pre-commit.com/#repository-local-hooks
 -   repo: local
     hooks:

ml-agents/mlagents/trainers/tf.py

-import tensorflow as tf
+# This should be the only place that we import tensorflow directly.
+# Everywhere else is caught by the banned-modules setting for flake8
+import tensorflow as tf  # noqa I201
 from distutils.version import LooseVersion
 
 

setup.cfg

     # Black tends to introduce things flake8 doesn't like, such as "line break before binary operator"
     # or whitespace before ':'. Rather than fight with black, just ignore these for now.
     W503, E203,
+    # flake-tidy-import adds this warning, which we don't really care about for now
+    I200
+
+banned-modules = tensorflow = use mlagents.tf instead (it handles tf2 compat).