use pre-built packages for ubuntu

[hannaeko]

Purpose

With the last release of Ubuntu, .deb packages can be used to install Zonemaster CLI.

Context

-

Changes

• Prefer pre built packages for ubuntu
• Keep the CPAN installation in a separate subsection

How to test this PR

Installation on Ubuntu should work. Use nightly packages to test.

host $ docker run --rm -it ubuntu:22.04 
container # apt update && apt install -y curl
container # curl -LOs https://package.zonemaster.net/setup.sh
container # nightly=yes sh setup.sh
container # zonemaster-cli --show-testcase --show-module --level info --no-ipv6 zonemaster.net
...
container # apt info zonemaster-cli
Package: zonemaster-cli
Version: 20220523200630-1+deb11ubuntu1
Priority: optional
Section: perl
...

[matsduf]

Preferably testing ("how to test this PR") should be done on the target system, not on Docker.

[hannaeko]

Preferably testing ("how to test this PR") should be done on the target system, not on Docker.

I am doing my tests on a VM, I provided instructions to test quickly but the instructions inside the container can be used inside a VM as well.