Your Composer dependencies require a PHP version ">= 7.2.5". You are running 7.2.0. in code example

Example 1: Composer detected issues in your platform: Your Composer dependencies require a PHP version ">= 7.3.0".

composer install --ignore-platform-reqs

Example 2: composer require with version

composer require vendor/package:version

composer require refinery29/test-util:0.10.2