Bump langchain from 0.2.1 to 0.3.7 in /python-rag-chatbot

Bumps [langchain](https://github.com/langchain-ai/langchain) from 0.2.1 to 0.3.7.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain==0.2.1...langchain==0.3.7)

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

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

python-rag-chatbot/requirements.txt

@@ -91,7 +91,7 @@ jsonschema==                               4.19.1
 jsonschema-specifications==2023.7.1
 kiwisolver==1.4.5
 kubernetes==29.0.0
-langchain==0.2.1
+langchain==0.3.7
 langchain-cli==0.0.24
 langchain-cohere==0.1.5
 langchain-community==0.2.1