pleiades-ansible ansible-playbook pleiades.yml fails on python-software-properties

[paregorios]

Tried:

ansible-playbook pleiades.yml -l staging_serenity --ask-become-pass

got:

BECOME password: 

PLAY [all] *****************************************************************************************************************************************************

TASK [Gathering Facts] *****************************************************************************************************************************************
[DEPRECATION WARNING]: Distribution Ubuntu 20.04 on host staging_serenity should use /usr/bin/python3, but is using /usr/bin/python for backward compatibility 
with prior Ansible releases. A future Ansible release will default to using the discovered platform python for this host. See 
https://docs.ansible.com/ansible/2.9/reference_appendices/interpreter_discovery.html for more information. This feature will be removed in version 2.12. 
Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.
ok: [staging_serenity]

TASK [Update apt cache] ****************************************************************************************************************************************
[WARNING]: Updating cache and auto-installing missing dependency: python-apt
ok: [staging_serenity]

TASK [Install repo management] *********************************************************************************************************************************
fatal: [staging_serenity]: FAILED! => {"changed": false, "msg": "No package matching 'python-software-properties' is available"}

PLAY RECAP *****************************************************************************************************************************************************
staging_serenity           : ok=2    changed=0    unreachable=0    failed=1    skipped=0    rescued=0    ignored=0   

On target server, tried:

sudo apt-get install python-software-properties 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package python-software-properties is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  software-properties-common

E: Package 'python-software-properties' has no installation candidate