Bump langchain from 0.0.270 to 0.0.321

Bumps [langchain](https://github.com/langchain-ai/langchain) from 0.0.270 to 0.0.321.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@v0.0.270...v0.0.321)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -16,7 +16,7 @@ mkdocs
 mkdocstrings[python]
 mkdocs-material
 sqlalchemy
-langchain==0.0.270
+langchain==0.0.321
 openai
 supabase
 SQLAlchemy