make add_track async for consistency

Author: chenosaurus

examples/local_audio/full_duplex.py

@@ -42,7 +42,7 @@ def on_track_subscribed(
         participant: rtc.RemoteParticipant,
     ):
         if track.kind == rtc.TrackKind.KIND_AUDIO:
-            player.add_track(track)
+            asyncio.create_task(player.add_track(track))
             logging.info("subscribed to audio from %s", participant.identity)
 
     room.on("track_subscribed", on_track_subscribed)

livekit-rtc/livekit/rtc/media_devices.py

@@ -235,7 +235,7 @@ def _callback(outdata: np.ndarray, frame_count: int, time_info: Any, status: Any
             blocksize=blocksize,
         )
 
-    def add_track(self, track: Track) -> None:
+    async def add_track(self, track: Track) -> None:
         """Add an audio track to the internal mixer for playback.
 
         This creates an `AudioStream` from the track and adds it to the internal