gguf quantized GGUF quantization imat imatrix static 16bit 8bit 6bit 5bit 4bit 3bit 2bit 1bit text-generation base_model:nvidia/Mistral-NeMo-Minitron-8B-Base base_model:quantized:nvidia/Mistral-NeMo-Minitron-8B-Base license:other region:us