Bump langchain in /End_to_end_Solutions/AOAISearchDemo/notebooks

Bumps [langchain](https://github.com/hwchase17/langchain) from 0.0.78 to 0.0.236.
- [Release notes](https://github.com/hwchase17/langchain/releases)
- [Commits](langchain-ai/langchain@v0.0.78...v0.0.236)

---
updated-dependencies:
- dependency-name: langchain
  dependency-type: direct:production
...

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

Author: dependabot[bot]

End_to_end_Solutions/AOAISearchDemo/notebooks/requirements.txt

@@ -1,4 +1,4 @@
 azure-identity==1.12.0
-langchain==0.0.78
+langchain==0.0.236
 openai==0.26.4
 azure-search-documents==11.4.0b3