What to support/test?

[NBajanca]

Define versions to support and test.

PHP

Currently, we are testing PHP 7.3.

We should, at least, test the PHP supported versions: 7.4 and 8.0.

However, PHPUnit 7 supported versions support are PHP 7.1 - PHP 7.3.

WordPress doesn't support newer versions off PHPUnit. Issue #46149 intends to solve this but looks stopped until the minimum required PHP version for WordPress is bumped to 7.1.

PHPCompatibilityWP (used in PHP_CodeSniffer) is configured to validate compatibility from PHP 5.6. The reason is WordPress current version supports this version. In this case we are using PHP 8.0.

WordPress

We test the latest version from WordPress, in PHP 7.3.

Should we test more versions? (this small WordPress StackExchange is divided between support one or two before the last one or "forcing" users to be updated for features and speed.)