This also removes the random compat library which is no longer necessary, and adjusts unit tests and CI workflows that no longer need to take PHP 5.6 into account.
Thank you for your service, PHP 5. Onwards!
Props SergeyBiryukov, mukesh27, dingo_d, audrasjb, jrf, costdev, azaozz, JavierCasares, hellofromTonya, samiamnot, spacedmonkey, masteradhoc, knutsp, garyjones, chanthaboune
Fixes#57345
git-svn-id: https://develop.svn.wordpress.org/trunk@56141 602fd350-edb4-49c9-b593-d223f7449a82