Upgrade to PHP 7.3.14

Summary: Reference: http://php.net/ChangeLog-7.php#7.3.14

Test Plan: Rebuild nasqueron/arcanist (rDARC) with this image as base, run arc which.

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D2236