fix background tasks

server.py

@@ -5,7 +5,7 @@ import random
 from fastapi import FastAPI
 from pydantic import BaseModel
 from fastapi.responses import FileResponse
-from fastapi.background import BackgroundTasks
+from fastapi import BackgroundTasks
 from starlette.requests import Request
 from kokoro import KPipeline
 import soundfile as sf
@@ -80,10 +80,13 @@ def health_check():
 async def receive(input_load: InputLoad, request: Request) -> FileResponse:
     audio_path = get_audio(input_load.text, input_load.language)
 
+    background_tasks = BackgroundTasks()
+    background_tasks.add_task(cleanup_temp_file, audio_path)
+
     return FileResponse(
         path=audio_path,
         media_type="audio/wav",
         filename="generated_audio.wav",
-        background=BackgroundTasks(cleanup_temp_file, audio_path)
+        background=background_tasks
     )