Update room_event_filter.yaml to use the OpenAPI allOf definition

This is just maintenance.

api/client-server/definitions/room_event_filter.yaml

@@ -13,23 +13,23 @@
 # limitations under the License.
 allOf:
 - $ref: event_filter.yaml
-title: RoomEventFilter
-properties:
-  not_rooms:
-    description: A list of room IDs to exclude. If this list is absent then no rooms
-      are excluded. A matching room will be excluded even if it is listed in the ``'rooms'``
-      filter.
-    items:
-      type: string
-    type: array
-  rooms:
-    description: A list of room IDs to include. If this list is absent then all rooms
-      are included.
-    items:
-      type: string
-    type: array
-  contains_url:
-    type: boolean
+- type: object
+  title: RoomEventFilter
+  properties:
+    not_rooms:
+      description: A list of room IDs to exclude. If this list is absent then no rooms
+        are excluded. A matching room will be excluded even if it is listed in the ``'rooms'``
+        filter.
+      items:
+        type: string
+      type: array
+    rooms:
+      description: A list of room IDs to include. If this list is absent then all rooms
+        are included.
+      items:
+        type: string
+      type: array
+    contains_url:
+      type: boolean
     description: If ``true``, includes only events with a url key in their content. If
       ``false``, excludes those events.
-type: object