Base on the skeleton file.

Trying some new podcasts.

I don't find any interesting content in those podcasts.

- Remove comments. They're from an old version and not very useful.
- Set default max_number.
- Set a restrictive filename policy. I needed it before for some
  podcasts but if I'm not sure why.

So it scans the audio library and finds new podcasts.

- Use the new skeleton pre-commit config.
- Add the Python hooks.
- Add the yamltool hook.
- Address new warning from Hadolint.

Not needed now that pre-commit runs in the .pre stage.

With the Toolbox container, I'm now on Python 3.9.

First of all, Poca 1.1 was released which contained my PR so using my
fork is no longer needed. Then various package updates from running
`pipenv update`.

My PR was merged and it also has other fixes I need.

Deduce the uid and gid from the volume owner and run as those. Don't
need to mount /etc/passwd and /etc/group inside the container (didn't
work with --user anyway). No hard-coded uids/ users anymore.

Don't use the host user home directory.

Install the version from my git fork which has a fix for a non-writable
config directory if the config file already exists.

This reverts commit fe7fdfb4. The image
is now available.

There aren't Alpine 3.13 tags for the Python image yet.

- More pre-commit hooks.
- Fixes from said hooks.
- pipenv updates.
- pre-commit updates.