chore(deps-dev): bump langgraph from 0.6.6 to 0.6.7

Bumps [langgraph](https://github.com/langchain-ai/langgraph) from 0.6.6 to 0.6.7.
- [Release notes](https://github.com/langchain-ai/langgraph/releases)
- [Commits](langchain-ai/langgraph@0.6.6...0.6.7)

---
updated-dependencies:
- dependency-name: langgraph
  dependency-version: 0.6.7
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]