feat(build): add oci labels

[Saschl]

Uses the docker metadata action to generate labels for the docker image which can be used by tools like renovate to display the proper source repo of the image and add the changelog for example. Inspired by: https://github.com/immich-app/immich/pull/17378

I've tested this on my fork and renovate picks up the labels correctly.

Note: this action can also be used to tag the image (and therefore replace the current "Set docker tags" step, but that can be done on a separate PR as I believe that warrants some discussion first)