feat: specify text output format in chat api decorator

app.py

@@ -13,7 +13,7 @@ client = OpenAI(
     }
 )
 
-@app.api()
+@app.api(outputs=["text"])
 def chat(message: str, history_json: list):
     # history_json should be a list of dictionaries like [{"role": "user", "content": "..."}, {"role": "assistant", "content": "..."}]
     messages = history_json + [{"role": "user", "content": message}]