Create a new GitHub Actions workflow which aims to continuously test our
official installation instructions. The way we do it is the following:
1. Create two jobs, one for the Debian-based distros, and one for Fedora
ones.
2. Copy the instructions from INSTALL.md into each job.
3. Create a matrix that runs the installation jobs in parallel, for each
supported distro and version.
The jobs will run only on 00:00 UTC, and not on every PR, since it
wouldn't make sense otherwise.
Fix#653
