handle audio added event

Author: TudorCRL

sdk/rt/speechmatics/rt/_async_client.py

@@ -96,6 +96,7 @@ def __init__(
         self.on(ServerMessageType.END_OF_TRANSCRIPT, self._on_eot)
         self.on(ServerMessageType.ERROR, self._on_error)
         self.on(ServerMessageType.WARNING, self._on_warning)
+        self.on(ServerMessageType.AUDIO_ADDED, self._on_audio_added)
 
         self._logger.debug("AsyncClient initialized (request_id=%s)", self._session.request_id)