Add pre-commit config

[matthieu-foucault]

No description provided.

[LindsayMacfarlane]

Hi @pbastia @dleard - what's the priority on this?

[dleard]

probably a low priority since we don't do much active development in this repo, but also low effort. Pre-commit is a code-quality tool that enforces some rules to ensure consistent formatting of code and commit messages as well as some other basic checks like checking that we aren't committing things that should be secret (like API keys).