chore(deps): Bump llama-index in /examples/langchain-chroma

Bumps [llama-index](https://github.com/run-llama/llama_index) from 0.11.7 to 0.11.12.
- [Release notes](https://github.com/run-llama/llama_index/releases)
- [Changelog](https://github.com/run-llama/llama_index/blob/main/CHANGELOG.md)
- [Commits](run-llama/llama_index@v0.11.7...v0.11.12)

---
updated-dependencies:
- dependency-name: llama-index
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

examples/langchain-chroma/requirements.txt

@@ -1,4 +1,4 @@
 langchain==0.3.0
 openai==1.45.1
 chromadb==0.5.5
-llama-index==0.11.7
+llama-index==0.11.12