Ignore LangGraph runtime files in Python.gitignore

[golden-horizon]

Link to the application or project's homepage

https://docs.langchain.com/oss/python/langgraph/overview

Reasons for making this change

LangGraph's langgraph dev command stores checkpointing and memory data in a .langgraph_api directory in the current working directory. These files are local runtime artifacts and should not be committed to source control.

This change is intentionally small and limited to the Python template.

Links to documentation supporting these rule changes

https://docs.langchain.com/langsmith/data-storage-and-privacy

https://docs.langchain.com/oss/python/langgraph/local-server

Merge and Approval Steps

• I have read the contribution guidelines and understand my PR will be closed if it doesn't meet these guidelines.

[github-actions]

This PR is stale because there have been no updates in 90 days. It will close after 365 days of inactivity. Leave a comment if you want to keep it open.

[dooleydevin]

Appreciate the contribution, but we already have a LangChain.gitignore template over here that covers this: https://github.com/github/gitignore/blob/main/LangChain.gitignore

Rather than add this to the more specific Python template, I'd ask that you pull the LangChain.gitignore template into your Python projects instead. That way we are not maintaining two templates for the same set of tools 👍

Going to close this out 🙇