fix: BillHandler cls -> self NameError causing Alipay notify infinite retry

backend/app/plugin/module_payment/notification/handlers/bill_handler.py

@@ -80,7 +80,7 @@ class BillHandler(BaseHandler[dict]):
                 auth, data.pay_no, "SUCCESS", data.model_dump(exclude_none=True)
             )
             # 通知到达，清除重试字段（无需再反查）
-            await cls._clear_transfer_retry(auth, data.pay_no)
+            await self._clear_transfer_retry(auth, data.pay_no)
             await OpenTransferService.open_return_service(auth, data.pay_no)