No distro has RPMs for python-rgain

[hairmare]

We need to get a python-rgain package into a distro at some point... @radiorabe currently uses a OBS-local build linked below

• https://pypi.org/project/rgain/
• https://pkgs.org/download/python-rgain
• https://build.opensuse.org/package/show/home:radiorabe:airtime:python-deps/python-rgain

There might be an issue since this package isn't officially maintained or rather, the maintainership status is unclear. Given that the implementation here doesn't support modern loudness algorithms like EBU R128 we might want to consider replacing this with something modern and maintained.