Update app.py

app.py

@@ -261,7 +261,7 @@ async def chat_completion(
                 key_manager.mark_success(api_key)
                 return response.json()
             
-            elif response.status_code == 429:
+            elif response.status_code == 403:
                 # Rate limit - try next key
                 key_manager.mark_failed(api_key)
                 api_key = key_manager.get_working_key()