Author: Eloy Lafuente (stronk7)
MDL-63421 env: Moodle 3.4.x and 3.5.x do not support PHP 7.3
http://git.moodle.org/gw?p=moodle.git;a=commit;h=8946ee7937a3d1e978cf96e61a4f7c141f143505
http://github.com/moodle/moodle/commit/8946ee7937a3d1e978cf96e61a4f7c141f143505
+ 3.5 en [unsupportedphpversion73,core_admin]