rPa579a974ebfe

PHPMailer: Remove use of each() function removed in PHP 8.0

Summary:
`each()` has been deprecated since PHP 7.2 and got removed in PHP 8.0 per https://www.php.net/manual/en/function.each.php

Replace it with a `foreach` construction.

Closes T15833

Test Plan: Carefully read the code; locally testing that construction per D25659#18155; compare to similar rP9623e667458821f696eb92e9dac5a2c9720af7af

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan…