Since it's all Drupal 8 there we should plan to move to PHP 7.4 i'd think. Targeting agaric for that now but can drop down to php 7.3 i think if we don't want to try that. But PHP 7.2 isn't good enough for a module, twig_tweak 3.0.0, that i'm trying
(speaking to wolcen about Elizabeth).
