Use docker metadata to generate tags and labels

[halkeye]

As the current docker image has no labels associated with it, especially not the opencontainer standard ones, tools like dependabot and renovate can't pull releasenotes or even link to commits.

regctl image config --format '{{ jsonPretty .Config.Labels }}' ghcr.io/axsuul/plex-media-server-exporter
null

vs

regctl image config --format '{{ jsonPretty .Config.Labels }}' ghcr.io/halkeye/plex-media-server-exporter:0.0.1
{
  "org.opencontainers.image.created": "2024-11-17T07:05:05.939Z",
  "org.opencontainers.image.description": "A better Prometheus exporter for Plex Media Server",
  "org.opencontainers.image.licenses": "MIT",
  "org.opencontainers.image.revision": "3ac5a255c6f8935bfd13eb31e883533dbbc02002",
  "org.opencontainers.image.source": "https://github.com/halkeye/plex-media-server-exporter",
  "org.opencontainers.image.title": "plex-media-server-exporter",
  "org.opencontainers.image.url": "https://github.com/halkeye/plex-media-server-exporter",
  "org.opencontainers.image.version": "0.0.1"
}