Update Optional[x] -> x | None and Union[x, y] to x | y (#26633)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

tests/lora/test_resolver.py

@@ -1,7 +1,6 @@
 # SPDX-License-Identifier: Apache-2.0
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
-from typing import Optional
 
 import pytest
 
@@ -14,7 +13,7 @@ class DummyLoRAResolver(LoRAResolver):
 
     async def resolve_lora(
         self, base_model_name: str, lora_name: str
-    ) -> Optional[LoRARequest]:
+    ) -> LoRARequest | None:
         if lora_name == "test_lora":
             return LoRARequest(
                 lora_name=lora_name,