Fixed type annotation for matrix-org#12437

StreamWorkerStore.get_stream_id_for_event_txn is not declared to return Optional[int] which is consistent with it's NoneType return when the allow_none = True

synapse/storage/databases/main/stream.py

@@ -806,8 +806,8 @@ def get_stream_id_for_event_txn(
         self,
         txn: LoggingTransaction,
         event_id: str,
-        allow_none=False,
-    ) -> int:
+        allow_none: bool = False,
+    ) -> Optional[int]:
         return self.db_pool.simple_select_one_onecol_txn(
             txn=txn,
             table="events",