Fixesguix/guix#466.
Previously those teams would exist at the organization-level but would
not be associated with the ‘guix/guix’ repository, thereby preventing
people from adding them as reviewers and from mentioning them.
* etc/teams.scm (repository-teams, add-repository-team): New Forgejo
requests.
(synchronize-teams): Call the latter.
Change-Id: Ibc6726cda66552ee9dd1df24d57b80f903712e67