unregister event callback when expect event received.

Author: cloudwebrtc

livekit-rtc/tests/test_change_video_quality.py

@@ -154,6 +154,7 @@ def _on_event(*args, **kwargs) -> None:
             return
         if predicate is None or predicate(*args, **kwargs):
             fut.set_result(args)
+        room.off(event, _on_event)
 
     room.on(event, _on_event)
     return fut