Add ruff linting and formatting CI

[vepadulano]

This is a proposal to add linting and formatting of Python files with ruff. If accepted, the wisest option would be to run a first time ruff check and ruff format once on the entire cmsstyle.py module. For now I just made a trivial change to the file to trigger the CI

[ttedeschi]

d0c65ee should have made cmsstyle.py pass ruff checks