Fix bug with streaming from URL

Author: PaulAsjes

src/elevenlabs/realtime/scribe.py

@@ -254,7 +254,7 @@ async def _connect_url(self, options: RealtimeUrlOptions) -> RealtimeConnection:
         # Build WebSocket URL
         ws_url = self._build_websocket_url(
             model_id=model_id,
-            audio_format=audio_format,
+            audio_format=audio_format.value,
             commit_strategy=commit_strategy.value,
             vad_silence_threshold_secs=vad_silence_threshold_secs,
             vad_threshold=vad_threshold,