Add Shields.io badge for GHCR when available

[ptr727]

See: https://github.com/badges/shields/issues/5594

[eggplants]

I have implemented eggplants/ghcr-badge on a trial basis:

https://ghcr-badge.herokuapp.com/ptr727/plexcleaner/tags

https://ghcr-badge.herokuapp.com/ptr727/plexcleaner/latest_tag

https://ghcr-badge.herokuapp.com/ptr727/plexcleaner/size

Please try!

[ptr727]

@eggplants, how would I do something as follows, or so I need to wait for the shields.io implementation:

![Docker Latest Pre-Release](https://img.shields.io/docker/v/ptr727/plexcleaner/develop?label=develop&logo=docker&color=orange)  
![GHCR Latest Pre-Release](https://ghcr-badge.herokuapp.com/ptr727/plexcleaner/develop_tag?logo=ghcr&color=orange)

[eggplants]

label parameter has been added.

https://ghcr-badge.herokuapp.com/ptr727/plexcleaner/tags?label=🤔&color=orange

Also /develop_tag has been added.

https://ghcr-badge.herokuapp.com/ptr727/plexcleaner/develop_tag?color=orange

and logo parameter is implementing now...

[ptr727]

Abandoning GHCR posting, too unreliable due to closed pipe errors that break the builds.