fix(multiplayer): repair PostgreSQL integration invariants

server/store/stalled_allocation_sql.go

@@ -44,7 +44,7 @@ const ExpireStalledAllocationsSQL = `WITH stalled AS (
             'event', 'state_changed',
             'revision', failed.revision,
             'resource_id', failed.match_id,
-            'occurred_at', $4,
+            'occurred_at', $4::timestamptz,
             'state', 'FAILED',
             'match_id', failed.match_id,
             'player_ids', COALESCE((
@@ -54,6 +54,7 @@ const ExpireStalledAllocationsSQL = `WITH stalled AS (
         )
     FROM failed
     ON CONFLICT DO NOTHING
+    RETURNING event_id
 )
 SELECT (SELECT count(*) FROM failed), (SELECT count(*) FROM requeued), (SELECT count(*) FROM events)`