Add #[ruma_api(body)] attr to get_room_event endpoint

ruma-client-api/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 Bug fixes:
 
+* Fix deserialization of `r0::room::get_room_event::Response`
 * More missing fields in `r0::sync::sync_events::Response` can be deserialized
 
 Breaking changes:

ruma-client-api/src/r0/room/get_room_event.rs

@@ -26,6 +26,7 @@ ruma_api! {
 
     response {
         /// Arbitrary JSON of the event body. Returns both room and state events.
+        #[ruma_api(body)]
         pub event: EventJson<AnyRoomEvent>,
     }