Replace flake8 with ruff

[cclauss]

Ruff supports over 500 lint rules and can be used to replace Flake8 (plus dozens of plugins), isort, pydocstyle, yesqa, eradicate, pyupgrade, and autoflake, all while executing (in Rust) tens or hundreds of times faster than any individual tool.

Changes to Python files were done with ruff --fix ..

[Cito]

Thanks, yes, we can try using ruff for this project.

Maybe also a good opportunity to go through the ignored rules and see if something can be improved here (but not in this same PR).