fix: use php-mpdf Debian autoloader instead of vendor/autoload.php

Switch from /usr/share/php/mpdf/vendor/autoload.php (which pollutes
Composer\InstalledVersions) to the new /usr/share/php/mpdf/autoload.php
provided by the fixed php-mpdf Debian package.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Vitexus

debian/autoload.php

@@ -7,7 +7,8 @@
 require_once '/usr/share/php/EaseHtml/autoload.php';
 require_once '/usr/share/php/AbraFlexi/autoload.php';
 require_once '/usr/share/php/IPEXB2B/autoload.php';
-require_once '/usr/share/php/mpdf/vendor/autoload.php';
+
+require_once '/usr/share/php/mpdf/autoload.php';
 
 // PSR-4 autoloader for SpojeNet\AbraFlexiIpex namespace
 spl_autoload_register(function (string $class): void {