build(deps-dev): bump langchain from 0.0.350 to 0.3.12

Bumps [langchain](https://github.com/langchain-ai/langchain) from 0.0.350 to 0.3.12.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@v0.0.350...langchain==0.3.12)

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

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

setup.cfg

@@ -57,7 +57,7 @@ exclude =
 # Add here test requirements (semicolon/line-separated)
 llm =
     llama-index
-    langchain==0.0.350
+    langchain==0.3.12
     overrides
 
 testing =