flake8 hook fix (#15693)
Summary:
This PR bypasses checking the user's configuration entirely and always use strict, since the CI considers it a hard failure if you can't pass flake8.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15693
Differential Revision: D13574889
Pulled By: suo
fbshipit-source-id: f5e1c5731cc49b6223b415317033c275bc7d4fec
