Move merge actions to notification (#9024)

* Move merge actions to notification

* Add missing mail notification

routers/repo/pull.go

@@ -716,8 +716,6 @@ func MergePullRequest(ctx *context.Context, form auth.MergePullRequestForm) {
 		return
 	}
 
-	notification.NotifyMergePullRequest(pr, ctx.User, ctx.Repo.GitRepo)
-
 	log.Trace("Pull request merged: %d", pr.ID)
 	ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(pr.Index))
 }