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

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

vllm/reasoning/deepseek_r1_reasoning_parser.py

@@ -2,7 +2,6 @@
 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project
 
 from collections.abc import Sequence
-from typing import Union
 
 from vllm.entrypoints.openai.protocol import DeltaMessage
 from vllm.reasoning.abs_reasoning_parsers import ReasoningParserManager
@@ -36,7 +35,7 @@ class DeepSeekR1ReasoningParser(BaseThinkingReasoningParser):
         previous_token_ids: Sequence[int],
         current_token_ids: Sequence[int],
         delta_token_ids: Sequence[int],
-    ) -> Union[DeltaMessage, None]:
+    ) -> DeltaMessage | None:
         ret = super().extract_reasoning_content_streaming(
             previous_text,
             current_text,