@msivanes thanks for the suggestion. It works with
pytorch=1.6
fastai=2.0.19
fastcore=1.3.1
On colab i did
pip uninstall torch -y
pip uninstall torch -y
# CUDA 10.1
!pip install torch==1.6.0+cu101 torchvision==0.7.0+cu101 -f https://download.pytorch.org/whl/torch_stable.html
pip install fastai==2.0.19
pip install fastcore==1.3.1