Flake8 fails with python 3.7

[KSchopmeyer]

Pyflake fails with python 3.7 in CI.

The failure is:
entrypoints-object-has-no-attribute-get in importlib_metadata

Probably traced down to same issue described in following issue

https://stackoverflow.com/questions/73929564/entrypoints-object-has-no-attribute-get-digital-ocean

importlib-meta released new version 5.0.0 on 1 Oct. Recommendation from this issue is that, at least for python>=3.7, limit
importlib-meta be limited to > 5.0.0 for python 3.7

Confrimed by issue python/importlib_metadata#411 that the problem exists and is probably an issue with python 3.7