Try out `ruff`

[anatoly-scherbakov]

astral-sh/ruff, having ⭐44.6k at the moment of writing this, is gaining great traction in Python development community. It combines code linting and formatting in one tool, and is also quite fast even on large codebases.

Shall we try it out?

[mielvds]

@davidlehn @BigBlueHat I think this is a necessary addition to have predictable PR's in a sustainable way. However, I see that rdflib chose a 88 ch linewrap instead of PyLD's 80 and there might be more. Should we apply this formatting on jsonld.py in a separate PR to discuss the concrete changes?