Setup pre-commit for repo

[pauloxnet]

I copied this from a similar issue in django-debug-toolbar:

To help lower barriers to contributing we should integrate pre-commit to the project. The main use for us would be to run the linter before a commit occurs to help prevent failed tests when PRs are opened. While this does change the setup time, it does conform to a growing practice. That conformity should theoretically be more accessible when compared to knowing to run make styles before committing.

jazzband/django-debug-toolbar#1485