Fix parameter name consistency in parse_server_event function

- Change function body to use 'str' parameter consistently
- Matches pattern used in OpenAI Realtime Beta service
- Fixes bug where parameter was named 'str' but body used 'message_str'
- Maintains consistency with existing codebase patterns

src/pipecat/services/gemini_multimodal_live/events.py

@@ -487,13 +487,13 @@ def parse_server_event(str):
         ServerEvent instance if parsing succeeds, None otherwise.
     """
     try:
-        evt_dict = json.loads(message_str)
+        evt_dict = json.loads(str)
         evt = ServerEvent.model_validate(evt_dict)
         return evt
     except Exception as e:
         logger.error(f"Error parsing server event: {e}")
         # Truncate raw message to avoid logging potentially sensitive or overly long data
-        truncated_message = message_str[:200] + "..." if len(message_str) > 200 else message_str
+        truncated_message = str[:200] + "..." if len(str) > 200 else str
         logger.error(f"Raw message (truncated): {truncated_message}")
         return None