chore(deps): Bump langchain from 1.2.12 to 1.3.9

Bumps [langchain](https://github.com/langchain-ai/langchain) from 1.2.12 to 1.3.9.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain==1.2.12...langchain==1.3.9)

---
updated-dependencies:
- dependency-name: langchain
  dependency-version: 1.3.9
  dependency-type: direct:production
...

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Author: dependabot[bot]