FetchContent is a CMake feature that allows you to fetch dependencies directly from online repositories. I have begun integrating it in all of my projects.

For example:
https://github.com/Journeyman-dev/png_wrapper.h

This would make libtcod a lot easier for people to get up and running. Also, this could simplify how you manage your GitHub actions workflows.