gguf ggml quantized q2_k q3_k_m q4_k_m q5_k_m q6_k q8_0 text-generation en zh dataset:Locutusque/UltraTextbooks-2.0 base_model:M4-ai/tau-0.5B base_model:quantized:M4-ai/tau-0.5B license:other region:us conversational