refac: modernize type annotations (PEP 604 / PEP 585)

backend/open_webui/tasks.py

@@ -1,12 +1,12 @@
 # tasks.py
 import asyncio
-from typing import Dict
-from uuid import uuid4
 import json
 import logging
-from redis.asyncio import Redis
-from fastapi import Request
 from typing import Dict, List, Optional
+from uuid import uuid4
+
+from fastapi import Request
+from redis.asyncio import Redis
 
 from open_webui.env import REDIS_KEY_PREFIX