Ansible (and ansible-core) is already installed in the runner images
which should be enough to interact with ansible galaxy without needing
to install any additional packages.
We need to use the latest versions because older nodejs runtimes have
been deprecated and removed some time ago.
As a bonus, the latest version of the setup-python action supports
caching pip dependencies out-of-the-box (setting the appropriate cache
option) so we can eliminate a few of the manual steps to setup
dependency caching.
Finally, I also bumped the python version to 3.13 which is what
currently ships in the Arch repositories, not that it really matters.
The ubuntu-20.04 runner is no longer available. Switch to latest so that
we don't need to keep updating this as time passes, we don't depend on
anything for a specific ubuntu version.
