Magento 2.3 runs on PHP 7.2.x but no later. I've done a DNF update on a Fedora 30 server which just bumped PHP to 7.3.8, so the Magento install is now borked. How can I slightly downgrade (!) the PHP version to get it back into compatibility? I don't mind clobbering the PHP install totally, or running these variants simultaneously, but searching for ways to do either is drawing a blank.
Come to think of it, I'd like to know how to stop this happening in future since Magento does seem to be a little behind the release PHP versions, which means it will probably just keep happening.
