transformers safetensors llama text-generation nm-vllm marlin int4 conversational arxiv:2210.17323 base_model:meta-llama/Llama-2-70b-chat-hf base_model:quantized:meta-llama/Llama-2-70b-chat-hf autotrain_compatible text-generation-inference endpoints_compatible 4-bit gptq region:us