Run flake8 for all .py files tracked in git

[matrss]

Purpose of PR?:

Fixes #2374.

Does this PR introduce a breaking change?

If the changes in this PR are manually verified, list down the scenarios covered::

Additional information for reviewer? : Mention if this PR is part of any design or a continuation of previous PRs

Does this PR results in some Documentation changes? If yes, include the list of Documentation changes

Checklist:

• [ ] Bug fix. Fixes #
• [ ] New feature (Non-API breaking changes that adds functionality)
• [ ] PR Title follows the convention of <type>: <subject>
• [ ] Commit has unit tests