Bring pands_stubs CI standards as close as possible to pandas

pandas_stubs snippets should be directly movable to pandas repository without causing issues with pre-commit hooks.

This is related to aspects like black, isort and file-endings, and is most easily-fixable by introducing pre-commit based on this configuration file: https://github.com/pandas-dev/pandas/blob/main/.pre-commit-config.yaml