peft llama2 quantization nlp transformers language-model bitsandbytes fine-tuned causal-lm dataset:timdettmers/openassistant-guanaco base_model:TinyPixel/Llama-2-7B-bf16-sharded base_model:adapter:TinyPixel/Llama-2-7B-bf16-sharded license:apache-2.0 region:us