build(deps): bump langchain from 1.3.5 to 1.4.0 (#335)

Bumps [langchain](https://github.com/langchain-ai/langchainjs) from 1.3.5 to 1.4.0.
- [Release notes](https://github.com/langchain-ai/langchainjs/releases)
- [Commits](https://github.com/langchain-ai/langchainjs/compare/@langchain/aws@1.3.5...@langchain/openai@1.4.0)

---
updated-dependencies:
- dependency-name: langchain
  dependency-version: 1.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]