Make natural join inner join

Co-authored-by: Erik Johnston <erik@matrix.org>

synapse/storage/databases/main/events_forward_extremities.py

@@ -88,8 +88,8 @@ class EventForwardExtremitiesStore(SQLBaseStore):
             sql = """
                 SELECT event_id, state_group, depth, received_ts
                 FROM event_forward_extremities
-                NATURAL JOIN event_to_state_groups
-                NATURAL JOIN events
+                INNER JOIN event_to_state_groups USING (event_id)
+                INNER JOIN events INNER JOIN USING (event_id)
                 WHERE room_id = ?
             """