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/tool_use/test_qwen3coder_tool_parser.py

@@ -3,7 +3,6 @@
 
 import json
 from collections.abc import Generator
-from typing import Optional
 
 import pytest
 
@@ -107,7 +106,7 @@ def stream_delta_message_generator(
     qwen3_tool_parser,
     qwen3_tokenizer: AnyTokenizer,
     model_output: str,
-    request: Optional[ChatCompletionRequest] = None,
+    request: ChatCompletionRequest | None = None,
 ) -> Generator[DeltaMessage, None, None]:
     all_token_ids = qwen3_tokenizer.encode(model_output, add_special_tokens=False)