Apply style using pre-commit

[tdegeus]

To expedite applying formatting, one could consider pre-commit instead of manual configuring the CI.

https://github.com/sciunto-org/python-bibtexparser/blob/57bdc8effe0d6fe418b577cf9ea0b75911a219a5/.github/workflows/linting_and_unittests.yml#L22

See e.g.

https://github.com/tdegeus/texplain/blob/main/.pre-commit-config.yaml https://github.com/tdegeus/texplain/blob/main/.github/workflows/pre-commit.yml

[MiWeiss]

Well, I am not a big fan of pre-commit. I found it to be slow and buggy. But then again the last time I gave it a try must be years ago. Thus, feel free to open a PR: No one is forced to use pre-commit locally, but it sure makes stuff nicer.