PHPUnit: Upgraded phpunit and config file format

composer.json

@@ -49,7 +49,7 @@
     "require-dev": {
         "dms/phpunit-arraysubset-asserts": "^0.2.0",
         "filp/whoops": "^2.3",
-        "phpunit/phpunit": "^9.1",
+        "phpunit/phpunit": "^9.3",
         "squizlabs/php_codesniffer": "^3.5",
         "symfony/var-dumper": "^5.0"
     },

phpunit.xml

@@ -1,6 +1,7 @@
+<?xml version="1.0"?>
 <phpunit
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/9.1/phpunit.xsd"
+    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
     bootstrap="./includes/autoload.php"
     colors="true"
 >
@@ -12,9 +13,9 @@
             <directory>./tests/Unit</directory>
         </testsuite>
     </testsuites>
-    <filter>
-        <whitelist>
+    <coverage>
+        <include>
             <directory>./src/</directory>
-        </whitelist>
-    </filter>
+        </include>
+    </coverage>
 </phpunit>