Update app.py

Imported PlainTextResponse from fastapi.responses

app.py

@@ -7,6 +7,8 @@ from dotenv import load_dotenv
 import os
 from deepgram import DeepgramClient, PrerecordedOptions
 from typing import List, Dict
+from fastapi.responses import PlainTextResponse
+
 
 
 # Load environment variables from .env file