Bump langchain-text-splitters in /ai/python-rag-chatbot

Bumps [langchain-text-splitters](https://github.com/langchain-ai/langchain) from 0.2.0 to 0.3.9.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-text-splitters==0.2.0...langchain-text-splitters==0.3.9)

---
updated-dependencies:
- dependency-name: langchain-text-splitters
  dependency-version: 0.3.9
  dependency-type: direct:production
...

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

Author: dependabot[bot]

ai/python-rag-chatbot/requirements.txt

@@ -96,7 +96,7 @@ langchain-cli==0.0.24
 langchain-cohere==0.1.5
 langchain-community==0.3.0
 langchain-core==0.2.2
-langchain-text-splitters==0.2.0
+langchain-text-splitters==0.3.9
 langchainhub==0.1.13
 langdetect==1.0.9
 langserve==0.2.1