LangGraph 3.0.0 Upgrade

[bsbodden]

Version 3.0.0 Breaking Changes (that I know of)

1. Python 3.9 support dropped - Now requires Python 3.10+
2. JSON deserialization restrictions added for security
3. Uses Python 3.10+ syntax (new union operators)

[andrewkcarter]

+1 for this. The langgraph-checkpointer 3.0.0 release addresses CVE-2025-64439 which I need to mitigate.

[andrewkcarter]

thank you