gguf quantized GGUF quantization imat imatrix static 8bit 6bit 5bit 4bit 3bit 2bit 1bit text-generation base_model:deepseek-ai/DeepSeek-Coder-V2-Instruct base_model:quantized:deepseek-ai/DeepSeek-Coder-V2-Instruct license:other region:us