Fix incorrect type hint in filtering code. (#12695)

changelog.d/12695.misc

@@ -0,0 +1 @@
+Fixes an incorrect type hint for `Filter._check_event_relations`.

synapse/api/filtering.py

@@ -19,6 +19,7 @@ from typing import (
     TYPE_CHECKING,
     Awaitable,
     Callable,
+    Collection,
     Dict,
     Iterable,
     List,
@@ -444,9 +445,9 @@ class Filter:
         return room_ids
 
     async def _check_event_relations(
-        self, events: Iterable[FilterEvent]
+        self, events: Collection[FilterEvent]
     ) -> List[FilterEvent]:
-        # The event IDs to check, mypy doesn't understand the ifinstance check.
+        # The event IDs to check, mypy doesn't understand the isinstance check.
         event_ids = [event.event_id for event in events if isinstance(event, EventBase)]  # type: ignore[attr-defined]
         event_ids_to_keep = set(
             await self._store.events_have_relations(