Bump langchain from 0.0.225 to 0.0.231

Bumps [langchain](https://github.com/hwchase17/langchain) from 0.0.225 to 0.0.231.
- [Release notes](https://github.com/hwchase17/langchain/releases)
- [Commits](langchain-ai/langchain@v0.0.225...v0.0.231)

---
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/requirements.txt

@@ -40,7 +40,7 @@ idna==3.4
     # via
     #   requests
     #   yarl
-langchain==0.0.225
+langchain==0.0.231
     # via -r requirements/requirements.in
 langchainplus-sdk==0.0.20
     # via langchain