Podqast: New data model

Thanks to @thigg podqast 2.20, the queue based podcast player, now works with a sql database model.

This is the first step for going to a 3 release with speed, ui, and backend updates. Please use
https://gitlab.com/cy8aer/podqast/-/issues for problems and ideas. You can discuss at Matrix #podqast:g3la.de

2.20 needs a data migration at first startup. It already can be downloaded at openrepos, harbour soon.