Fix: dont use importlib_metadata v5.0 due to deprecated behavior and interface. (#608)

Summary:
Pull Request resolved: #608

Temporarily peg importlib_metadata to <5.0 due do breaking changes (python/importlib_metadata#409) for CPython 3.7

The right fix is to use `metadata.entry_points(group=group, name=name)`, however typechecker does not recognize the changes (python/importlib_metadata@7e5bae4)

Reviewed By: d4l3k

Differential Revision: D40053701

fbshipit-source-id: 9860594c5283ce3f24f7284dff98447aa2df0604

Author: kurman

dev-requirements.txt

@@ -7,7 +7,7 @@ classy-vision>=0.6.0
 flake8==3.9.0
 fsspec[s3]==2022.1.0
 hydra-core
-importlib-metadata
+importlib-metadata<5.0
 ipython
 kfp==1.8.9
 moto==3.0.2