[GITEA] the ref of a scheduled action is always the default branch

Since a scheduled action is only run from the default branch, it
cannot be anything else.

Refs: https://codeberg.org/forgejo/forgejo/issues/1926
(cherry picked from commit eff0822856)
(cherry picked from commit 2b1aa50bd1)

Conflicts:
	services/actions/notifier_helper.go
	https://codeberg.org/forgejo/forgejo/pulls/2075
(cherry picked from commit 4ff3474fc0)
(cherry picked from commit 07b8887031)
(cherry picked from commit cbecdd618d)

services/actions/notifier_helper.go

@@ -461,7 +461,7 @@ func handleSchedules(
 			OwnerID:       input.Repo.OwnerID,
 			WorkflowID:    dwf.EntryName,
 			TriggerUserID: input.Doer.ID,
-			Ref:           ref,
+			Ref:           input.Repo.DefaultBranch,
 			CommitSHA:     commit.ID.String(),
 			Event:         input.Event,
 			EventPayload:  string(p),