New comment by emacsomancer on void-packages repository

https://github.com/void-linux/void-packages/issues/12517#issuecomment-502904151
Comment:
@sass432 as a quick work-around, you could install `pdftk` via [Nix's standalone package manager](https://nixos.org/nix/manual/). I tried this, and can confirm it works with Void's `gscan2pdf`.