Add Mistral 7B model support

[flaneur2020]

No description provided.

[b41sh]

Hi, @flaneur2020 I'd like to work on this, can you assign this issue to me?

[flaneur2020]

@b41sh thank you for the contribution! you could download the mistral model from links like https://huggingface.co/TheBloke/Mistral-7B-v0.1-GGUF/tree/main

i recommend using a q8_0 model, as it's the most optimized one and tested quantization format

(but i'm a bit afraid of there's a risk that we might already supported mistral model as it's also considered as a llama model, it need a confirmation though)

[flaneur2020]

I'm sorry, I grabbed this issue in #155 , mistral actually did not make difference with llama, but there's a bug in GQA implementation, it works well after this bug get resolved.

i've splitted more model support related tasks in: #157 , we can make some investigations together to make these models work with crabml

[b41sh]

Ok, I will continue work on those models.