Error reason:

The code uses GPU accelerated torch, but I downloaded the C + + version of torch. Use PIP list to find packages as follows:

Solution:

Uninstall torch and torchvision, and then use command pip install torch==1.7.0+cu110 torchvision==0.8.0+cu110 torchaudio==0.7.0 -f https://download.pytorch.org/whl/torch_stable.html to install it.