tests: Add test for updating from oci remote (currently broken)

This is currently failing with:
  Can't pull from untrusted non-gpg verified remote

Closes: #2891
Approved by: alexlarsson
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f