chore(deps): bump pytest to 9.0.3 (#36801)

CVE-2025-71176 (medium severity)

All are dev-only (test dependency group) — no impact on published
packages.

### Why syrupy was also bumped

syrupy 4.x (`<5.0.0`) constrains pytest to `<9.0.0`, blocking the CVE
fix. Widening to `<6.0.0` allows syrupy 5.x which supports pytest 9.x.

libs/partners/openai/tests/integration_tests/chat_models/test_azure.py

@@ -39,7 +39,6 @@ def _get_llm(**kwargs: Any) -> AzureChatOpenAI:
     )
 
 
-@pytest.mark.scheduled
 @pytest.fixture
 def llm() -> AzureChatOpenAI:
     return _get_llm(max_tokens=50)