Adding Pixtral from Mistral Team

[amitbcp]

Hey @kennymckormick @jinyu121 @FangXinyu-0913 :

I was planning to add : https://huggingface.co/mistralai/Pixtral-12B-2409 model to the eval framework.

The Mixtral team recommends using vllm for inference. Is it okay to introduce that dependency for the repo ?

If its okay I can go ahead and create a PR for the same