By setting the `desired_package_state` variable we can change if ansible
should only ensure that the packages exist on the system (`present`) or
that they are also updated to their latest version (`latest`).
One inventory targets a local machine (`inv-local.yaml`, chosen by default)
while the other targets a chrooted installation accessible from another
system, usually in the `/mnt/void` directory (`inv-chroot.yaml`, has to
be called like `ansible-playbook -i inv-chroot.yaml`).