add cleanlab

[jwmueller]

Learn more:

https://www.technologyreview.com/2024/04/25/1091835/chatbot-hallucination-new-tool-trustworthy-language-model/

https://analyticsindiamag.com/topics/top-ai-hallucination-detection-tools/

https://cleanlab.ai/blog/rag-tlm-hallucination-benchmarking/

https://labelstud.io/blog/llm-evaluation-comparing-four-methods-to-automatically-detect-errors/

https://github.com/cleanlab/cleanlab