Ensure that Forum does not get special core treatment

It looks like this module has a release now: https://www.drupal.org/project/forum →

This one did not end up with a doubled namespace, so I think everything is done here. It was removed from special core treatment with https://git.drupalcode.org/project/project_composer/-/commit/41c9d1fee39...

Automatically closed - issue fixed for 2 weeks with no activity.