gguf reasoning preference_learning kto text-generation dataset:openbmb/UltraFeedback dataset:openbmb/UltraInteract_pair arxiv:2402.01306 base_model:openbmb/Eurus-7b-kto base_model:quantized:openbmb/Eurus-7b-kto license:apache-2.0 endpoints_compatible region:us conversational