don't fail on go2rtc stream with no url (#8839)

frigate/http.py

@@ -1358,7 +1358,7 @@ def go2rtc_streams():
     stream_data = r.json()
     for data in stream_data.values():
         for producer in data["producers"]:
-            producer["url"] = clean_camera_user_pass(producer["url"])
+            producer["url"] = clean_camera_user_pass(producer.get("url", ""))
     return jsonify(stream_data)