[Bugfix] Fix asyncio.Task not being subscriptable (#4623)

vllm/engine/async_llm_engine.py

@@ -1,8 +1,8 @@
 import asyncio
 import time
 from functools import partial
-from typing import (Any, AsyncIterator, Callable, Dict, Iterable, List,
-                    Optional, Set, Tuple, Type, Union)
+from typing import (AsyncIterator, Callable, Dict, Iterable, List, Optional,
+                    Set, Tuple, Type, Union)
 
 from transformers import PreTrainedTokenizer
 
@@ -327,7 +327,7 @@ class AsyncLLMEngine:
         # We need to keep a reference to unshielded
         # task as well to prevent it from being garbage
         # collected
-        self._background_loop_unshielded: Optional[asyncio.Task[Any]] = None
+        self._background_loop_unshielded: Optional[asyncio.Task] = None
         self.start_engine_loop = start_engine_loop
         self._errored_with: Optional[BaseException] = None