try fixing valid key issue

main.py

@@ -23,7 +23,7 @@ VALID_API_KEYS = os.environ.get("api_key")
 @app.middleware("http")
 async def verify_api_key(request, call_next):
     api_key = request.headers.get("x-api-key")
-    if api_key not in VALID_API_KEYS:
+    if api_key is None or api_key not in VALID_API_KEYS:
         raise HTTPException(status_code=403, detail="Unauthorized")
     response = await call_next(request)
     return response