docker_redner: Ease running the command by providing same default as `docker_dev_start --start-redner`.

Factorize postgres connection code.

 docker_dev_start and docker_pylint: do not duplicate mount point for songs when they are correctly defined in python_packages.

--user is not compatible with the use of venv.

Also add a workaround a hatchling/setuptools-scm bug.

 update package classifiers