chore(deps-dev): bump langchain-text-splitters

Bumps [langchain-text-splitters](https://github.com/langchain-ai/langchain) from 0.3.5 to 0.3.9.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@langchain-text-splitters==0.3.5...langchain-text-splitters==0.3.9)

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

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Author: dependabot[bot]