Figure out why the linter is failing on github actions but not locally

[ericdill]

Running make check on Github Actions fails with the following error:

Run make check
Skipped 2 files
/opt/hostedtoolcache/Python/3.7.8/x64/lib/python3.7/site-packages/isort/main.py:907: UserWarning: W0501: The following deprecated CLI flags were used and ignored: --recursive!
  "W0501: The following deprecated CLI flags were used and ignored: "
/opt/hostedtoolcache/Python/3.7.8/x64/lib/python3.7/site-packages/isort/main.py:911: UserWarning: W0500: Please see the 5.0.0 Upgrade guide: https://timothycrosley.github.io/isort/docs/upgrade_guides/5.0.0/
  "W0500: Please see the 5.0.0 Upgrade guide: "
would reformat /home/runner/work/s3contents/s3contents/s3contents/genericmanager.py
would reformat /home/runner/work/s3contents/s3contents/s3contents/s3_fs.py
would reformat /home/runner/work/s3contents/s3contents/s3contents/tests/test_gcsmanager.py
would reformat /home/runner/work/s3contents/s3contents/s3contents/tests/test_gcsmanager_with_prefix.py
would reformat /home/runner/work/s3contents/s3contents/s3contents/tests/test_s3manager_with_prefix.py
would reformat /home/runner/work/s3contents/s3contents/s3contents/tests/test_s3manager.py
Oh no! 💥 💔 💥
6 files would be reformatted, 11 files would be left unchanged.
make: *** [check] Error 1
Makefile:61: recipe for target 'check' failed
##[error]Process completed with exit code 2.

make check does not fail like this locally. One approach to debugging would be to add --diff to the Makefile under the check section. That way we could at least see what black is complaining about

[danielfrg]

This is fixed now