This GitHub action installs qpdf:

- uses: yegor256/qpdf-action@master

I'm sorry, but it works on Ubuntu only. If you know how to make it work no MacOS and Windows, please, submit a pull request, I will gladly accept it.

Also, there is no caching now. This means that every time it will take about 10 minutes to install qpdf, on every single build. This is terrible, but I don't know how to fix this. If you know, please submit a pull request.