fix: enable receive sound in pymumble

Without set_receive_sound(True), pymumble silently drops all
incoming audio packets.

src/tuimble/client.py

@@ -145,6 +145,7 @@ class MumbleClient:
             reconnect=False,
         )
         self._mumble.set_codec_profile("audio")
+        self._mumble.set_receive_sound(True)
         self._register_callbacks()
 
         self._mumble.start()