Add change title notification for issues (#8061)

routers/repo/issue.go

@@ -1045,11 +1045,14 @@ func UpdateIssueTitle(ctx *context.Context) {
 		return
 	}
 
+	oldTitle := issue.Title
 	if err := issue.ChangeTitle(ctx.User, title); err != nil {
 		ctx.ServerError("ChangeTitle", err)
 		return
 	}
 
+	notification.NotifyIssueChangeTitle(ctx.User, issue, oldTitle)
+
 	ctx.JSON(200, map[string]interface{}{
 		"title": issue.Title,
 	})