chore(deps): bump langsmith

Bumps [langsmith](https://github.com/langchain-ai/langsmith-sdk) from 0.5.6 to 0.5.18.
- [Release notes](https://github.com/langchain-ai/langsmith-sdk/releases)
- [Commits](https://github.com/langchain-ai/langsmith-sdk/commits)

---
updated-dependencies:
- dependency-name: langsmith
  dependency-version: 0.5.18
  dependency-type: indirect
...

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Author: dependabot[bot]