Streaming zipformer for sherpa-onnx
The torchscript model is from https://huggingface.co./pfluo/k2fsa-zipformer-chinese-english-mixed
The training code is from https://github.com/k2-fsa/icefall/tree/master/egs/librispeech/ASR/pruned_transducer_stateless7_streaming