fixed linting

lightrag/api/lightrag_server.py

@@ -1,4 +1,13 @@
-from fastapi import FastAPI, HTTPException, File, UploadFile, Form, Request, BackgroundTasks
+from fastapi import (
+    FastAPI,
+    HTTPException,
+    File,
+    UploadFile,
+    Form,
+    Request,
+    BackgroundTasks,
+)
+
 # Backend (Python)
 # Add this to store progress globally
 from typing import Dict