Troyfeng116/linting tests

[troyfeng116]

@niansong1996 I think this is ready to merge. Basically pulled in the changes from #25 but for GH actions instead of Travis, and with updated tests. Some todos:

• Remove ignoring rule E501 from setup.cf. This rule (max line length) is currently ignored because flake8 does not ignore comments/docstrings for line length. We will eventually want to trim comments/docstrings to 88 to match black standards

This PR does touch pretty much every file so might cause conflicts with other branches, feel free to merge whenever convenient

[niansong1996]

I think it's better to merge right now before more changes showing up