Upgraded PHPUnit schema URL to 10.3

phpunit.xml.dist

 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.2/phpunit.xsd"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.3/phpunit.xsd"
     backupGlobals="false"
     bootstrap="vendor/autoload.php"
     colors="true"