peft tensorboard safetensors PyTorch Transformers trl sft BitsAndBytes PEFT QLoRA en dataset:databricks/databricks-dolly-15k arxiv:2205.14135 arxiv:2305.14314 base_model:meta-llama/Llama-2-7b-chat base_model:adapter:meta-llama/Llama-2-7b-chat license:mit region:us