chore(deps): bump langchain from 0.0.348 to 0.0.351

Bumps [langchain](https://github.com/langchain-ai/langchain) from 0.0.348 to 0.0.351.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@v0.0.348...v0.0.351)

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

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

Author: dependabot[bot]

requirements.txt

@@ -24,7 +24,7 @@ python-dotenv==1.0.0
 # production
 # ------------
 python-decouple==3.8
-langchain==0.0.348
+langchain==0.0.351
 langchainhub==0.1.14
 langchain-experimental==0.0.45
 openai==1.3.7