Adjust python-apt package to be findable on newer Debian/Ubuntu versions

[Ianvdl]

At the moment python-apt is installed on Debian-based distros using the following:

 - name: Install python-apt package
   ansible.builtin.package:
     name: python-apt
     state: present
   when:
     - ansible_os_family == 'Debian'

On newer versions of these distros, the python-apt package has been superseded by python3-apt, so the playbook fails at this point. Since all other references in roles/install_dbserver/tasks/validate_install_dbserver.yml are already configured to use the python3 versions, e.g.:

grep python3 roles/install_dbserver/tasks/validate_install_dbserver.yml
        'python3-pycurl', 'python3-libselinux', 'python3-psycopg2', 'glibc-langpack-en'
        'python3-pip', 'python3-psycopg2'
        'ca-certificates', 'python3-pycurl', 'python3-psycopg2', 'postgresql-' + pg_version | string,
        'python3-pip', 'python3-psycopg2', 'edb-as' + pg_version | string + '-server',

We are probably safe to proceed with this change.

[vibhorkumar123]

I am worried about what would happen to the old version of Debian. Would you like to add a check for the Debian version and, based on that, use python3-apt?

[Ianvdl]

I could do that - do you think it's necessary? Debian removed python-apt five years ago, as far as I can tell, along with Python 2.7.

[Ianvdl]

Updated the PR to use python-apt for Debian 9 and 10 (Stretch and Buster), and python3-apt for Debian 11 and 12 (Bullseye and Bookworm).

[vibhorkumar123]

LGTM!