partners[lint]: run pyupgrade to get code in line with 3.9 standards (#30781)

Using `pyupgrade` to get all `partners` code up to 3.9 standards
(mostly, fixing old `typing` imports).

libs/partners/anthropic/tests/integration_tests/test_llms.py

@@ -1,6 +1,6 @@
 """Test Anthropic API wrapper."""
 
-from typing import Generator
+from collections.abc import Generator
 
 import pytest
 from langchain_core.callbacks import CallbackManager