Add linnting, isort and black as pre commit hooks

[jakobkolb]

To avoid unnecessary CI failures, do code formatting automatically. Also, run linting and reject commit if linting does not pass.

[benmaier]

how does automatic formatting work? is there a vim plugin?

[jakobkolb]

Well maybe there is a vim plugin, i wouldn't know. My preferred way is to install a formatter (I like black) and then, in your project directory, just run black .

[benmaier]

amazing, thanks

[davhin]

I have done black+flake8 pre-commit hook in the datenspende repo, I can take over this task