Add pre-commit for python script ?

As part of TODO list of #954, pre-commit could be use to progressively modernise python code and make sure all developpers use same formatting method.

A nice pre-commit config for python : https://github.com/opengisch/QgisModelBaker/blob/master/.pre-commit-config.yaml

This ticket is opened for discussion.

TODO list :

• Create .yaml config
• Update documentation to setup pre-commit on your PC
• Run pre-commit on all files ?