I’m on a mac, and I had this too, I googled around a bit and pip install -U ipywidgets did it for me. I’m not using venv or anything like that. Total python novice, doing it all quick’n’dirty.
If that works you might get caught out on the creation of the image from the upload a few cells down. Looking at the 2020 course thread on this issue got me unblocked widgets.FileUpload() not working - #29 by ipetrousov