RuntimeError: Failed to export an ONNX attribute, since it's not constant, please try to make things

这是一个Pytorch1.1版本pytorch模型转onnx的bug

参考：https://blog.youkuaiyun.com/Cxiazaiyu/article/details/91129657

解决方法：

1. pip install -i https://pypi.tuna.tsinghua.edu.cn/simple torch==1.0.1

2. pip install -i https://pypi.tuna.tsinghua.edu.cn/simple torchvision==0.2.1