Provide variables for "PHP supported by core (previous version)"

Migrated issue

Reported by: dave reid

Related to !63 (merged)

Problem/Motivation

This is a follow-up to https://www.drupal.org/project/gitlab_templates/issues/3394905

I'd like to have variables set to the minimum PHP supported by Drupal core so that I do not have to maintain them in my configuration.

According to https://www.drupal.org/docs/getting-started/system-requirements/php-requirements for Drupal 9 the minimum is 7.3 and the maximum is 8.1.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes