Pydantic BaseModel type for updates using Command

[larsenweigle]

I wasn’t sure if this should really be considered a “new feature” since it is such a small update, but I think it would be nice to allow users to pass updates that are of type BaseModel in a Command.

In most of my projects involving LangGraph, I prefer to use Pydantic BaseModel states for data validation and cleaner code. I find the code much more readable when I can pass these custom states in the update attribute of the new Command class.

I’ve already made a draft PR here.