Raise minimum PHPUnit version

Author: mmoll

composer.json

@@ -34,7 +34,7 @@
         "phan/phan": "^5.4.5",
         "phpstan/phpstan": "^1.12",
         "phpstan/phpstan-strict-rules": "^1.6",
-        "phpunit/phpunit": "^8.5.36 || ^9.6.15",
+        "phpunit/phpunit": "^9.6.15",
         "psalm/plugin-phpunit": "^0.19",
         "sabre/event": "^5.1.6",
         "symfony/filesystem": ">= 5.4.45",

phpunit.xml.dist

@@ -1,5 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
         backupGlobals="true"
         beStrictAboutTestsThatDoNotTestAnything="false"
         bootstrap="tests/bootstrap.php"
@@ -9,9 +11,9 @@
             <file>vendor/squizlabs/php_codesniffer/tests/Standards/AllSniffs.php</file>
         </testsuite>
     </testsuites>
-    <filter>
-        <whitelist processUncoveredFilesFromWhitelist="false">
+    <coverage processUncoveredFiles="false">
+        <include>
             <directory suffix=".php">./MO4/Sniffs</directory>
-        </whitelist>
-    </filter>
+        </include>
+    </coverage>
 </phpunit>