Update copyright year
Through
````
gsed -i -e 's+2018-2021+2018-2022+g' *.ipynb
gsed -i -e 's+2018-2021+2018-2022+g' */*.ipynb
gsed -i -e 's+2018-2021+2018-2022+g' */*/*.ipynb
````
(`gsed` in macOS to use the GNU version which correctly handles the inplace option - on Linux just `sed` is ok).
issue