Use Ruff for code linting and checking

[WhyNotHugo]

Ruff does the same as flake8(+plugins)+pyupgrade+isort, but much faster and can also automatically fix many of these quirks too.

It ignores all files that are ignored by git, so all the exclude rules are not necessary.

I have left isort-related rules out for now since they results in some changes which might add noise at this point.

[WhyNotHugo]

Darn, isort seems to be broken when run via pre-commit. It might be a good time to replace it too TBH.