sentence-transformers safetensors mpnet sentence-similarity feature-extraction dataset_size:100K<n<1M loss:MultipleNegativesRankingLoss en arxiv:1908.10084 arxiv:1705.00652 base_model:microsoft/mpnet-base base_model:finetune:microsoft/mpnet-base license:apache-2.0 model-index autotrain_compatible endpoints_compatible region:us