Remove dependency on pyalpm/libalpm
The dependency on pyalpm pulls in libalpm, which is not packaged on e.g. Debian based distributions (external CI will not work as it is often Ubuntu based - e.g. can't build docs on readthedocs.org because it pulls in libalpm).
Currently the only place where pyalpm is used is the Version
model that offers convenience methods to compare versions using vercmp
.