Change Python formatting: black → ruff

[Dimitri Papadopoulos Orfanos]

Is your feature request related to a problem? Please describe.

Change the formatting from black to ruff, as a complement to #1771.

Many scientific packages are making the switch in order to:

• reduce the number of tools they depend on,
• make sure linting and formatting are consistent,
• improve formatting performance.

Describe the solution you'd like

Switch from black to ruff-format in .pre-commit-config.yaml/pyproject.toml.