chore: Update third party dependencies

Author: mitelg

UPGRADE-5.7.md

@@ -32,7 +32,7 @@ This changelog references changes done in Shopware 5.7 patch versions.
 * Updated `mpdf/mpdf` to version 8.2.4
 * Updated `laminas/laminas-code` to version 4.14.0 for PHP 8.1 and newer
 * Updated `laminas/laminas-escaper` to version 2.13.0 for PHP 8.1 and newer
-* Updated `phpunit/phpuit` to version 9.6.11
+* Updated `phpunit/phpunit` to version 9.6.21
 * Updated `setasign/fpdf` to version 1.8.6
 * Updated `setasign/fpdi` to version 2.6.1
 * Updated `symfony/polyfill-php80` to version 1.31.0