pydantic 2.9.0b2 on Python PyPI

What's Changed

Bump pydantic-core to v2.23.1 and other minor version bumps by @sydney-runkle in #10269

Raise helpful warning when self isn't returned from model validator by @sydney-runkle in #10255

Update namespace stack with already copied namespace by @sydney-runkle in #10267

Fix new warnings assertions to use pytest.warns() by @mgorny in #10241
Fix a crash when cleaning the namespace in ModelMetaclass by @Viicos in #10242
Fix parent namespace issue with model rebuilds by @sydney-runkle in #10257
Remove defaults filter for namespace by @sydney-runkle in #10261
Use identity instead of equality after validating model in __init__ by @Viicos in #10264
Support BigInt serialization for int subclasses by @kxx317 in pydantic/pydantic-core#1417