Fix: Reference

Author: localheinz

test/Phar/phpunit.xml

@@ -1,6 +1,6 @@
 <phpunit
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="../../vendor/phpunit/phpunit/phpunit.xsd"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.4/phpunit.xsd"
     beStrictAboutChangesToGlobalState="true"
     beStrictAboutOutputDuringTests="true"
     beStrictAboutTestsThatDoNotTestAnything="true"