fix: JsonPlusRedisSerializer handling proper Serialization of Interrupt

[keenborder786]

Takes care of the following issue raised in langchain: langchain-ai/langchain#33556

[keenborder786]

@bsbodden please review

[bsbodden]

This PR addresses a real issue, but conflicts with PR #112. Needs modifications before merging.

Your PR includes this code (lines 43-52 in diff):

try:
    from langgraph.types import Interrupt

    if isinstance(obj, Interrupt):
        # Serialize Interrupt as a constructor format for proper deserialization
        return super().dumps(obj)
except ImportError:
    pass

This conflicts with PR #112 which removes the try/except pattern and changes dumps() to use orjson.dumps(obj, default=self._default) directly.

PR #112 establishes the correct pattern: always use orjson with the default handler

rebase this PR and:

1. Remove the special Interrupt handling in dumps() (lines 43-52)

   • The _default handler should already serialize Interrupts correctly
   • Test to confirm this works

2. Update tests if needed

Great work identifying and fixing this bug! 🎉

[keenborder786]

@bsbodden please check now

[keenborder786]

@bsbodden is their any other issue?

[keenborder786]

@bsbodden