Add PHP 7.4 support

[geerlingguy]

Issue Type

• Feature Idea

Your Environment

N/A

Your OS

N/A

Summary

PHP 7.4 is released now, and it seems to work okay in my preliminary testing.

I already support it in the geerlingguy.php-versions role 4.0.0 and later (note that that version also deprecates PHP 7.1, since it's no longer supported—and also means that 5.6 and 7.0 don't have any support anymore, not even marginal/broken support like they did up to now). See: geerlingguy/ansible-role-php-versions#43

So while this update would not break anything existing, it could break some people's builds if they have really old defaults (like php_version: 5.6) in their config.yml files and they've just upgraded Drupal VM over and over from like 3.x to 5.x.