build(deps): bump llama-index in /examples/langchain-chroma

Bumps [llama-index](https://github.com/run-llama/llama_index) from 0.6.2 to 0.12.9.
- [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@v0.6.2...v0.12.9)

---
updated-dependencies:
- dependency-name: llama-index
  dependency-type: direct:production
...

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

Author: dependabot[bot]

examples/langchain-chroma/requirements.txt

@@ -1,4 +1,4 @@
 langchain==0.0.160
 openai==0.27.6
 chromadb==0.3.21
-llama-index==0.6.2
+llama-index==0.12.9