Models removed: replit-code-v1.5-3b and openhermes-2-mistral-7b

We have removed support for replit-code-v1.5-3b and openhermes-2-mistral-7b. There are no immediate plans to add these models back. If you were a user who enjoyed openhermes-2-mistral-7b, try instead using our in-house models, pplx-7b-chat, pplx-70b-chat!