Gitea - switched image to be ARM compatible

[gOOvER]

Description

I accidentally used the Debian Imstall image; this is not ARM compatible. Image has been updated to the official Bullseye image

Checklist for all submissions

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you tested and reviewed your changes with confidence that everything works?
• Did you branch your changes and PR from that branch and not from your master branch?
  • If not, why?:

[QuintenQVD0]

LGTM! thx