Linting

[mhubii]

• Runs linting on push / PR. Documentation: https://black.readthedocs.io/en/stable/integrations/github_actions.html
• Does not commit changes
• Adds status badges to readme

Note this PR fails files

• https://github.com/cai4cai/torchsparsegradutils/blob/main/torchsparsegradutils/utils/lsmr.py
• https://github.com/cai4cai/torchsparsegradutils/blob/main/torchsparsegradutils/utils/random_sparse.py

Which I formatted.

@theo-barfoot

Maybe you could add isort action next https://pycqa.github.io/isort/docs/configuration/github_action.html , not that it adds any value