Prune old images and charts

[lvlcn-t]

Is there an existing feature request for this?

• I have searched the existing issues

Problem Description

The github container registry is getting/will get really big because we're pushing all commit images and charts into it.

In order not to lose clarity we should prune old images and charts.

Solution Description

Add a new github action that runs periodically that prunes all images older than 7 days or so.

I've found a github action that can do this, but it's unmaintained. I've linked it below.

Additionally we should think about only packaging and pushing the charts if they've changed.

Who can address the issue?

Everyone who wants to explore github actions.

Additional Context

https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#schedule
https://github.com/vlaurin/action-ghcr-prune