diff --git a/phpunit.xml b/phpunit.xml
index f83040094..71345e1cb 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,27 +1,13 @@
-<phpunit
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/7.1/phpunit.xsd"
-    backupGlobals="false"
-    backupStaticAttributes="false"
-    beStrictAboutTestsThatDoNotTestAnything="true"
-    beStrictAboutChangesToGlobalState="true"
-    beStrictAboutOutputDuringTests="true"
-    colors="true"
-    convertErrorsToExceptions="true"
-    convertNoticesToExceptions="true"
-    convertWarningsToExceptions="true"
-    processIsolation="false"
-    stopOnFailure="false"
-    bootstrap="tests/bootstrap.php"
->
-    <testsuites>
-        <testsuite name="Test Suite">
-            <directory>./tests/</directory>
-        </testsuite>
-    </testsuites>
-    <filter>
-        <whitelist processUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">./src/</directory>
-        </whitelist>
-    </filter>
+<?xml version="1.0"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd" backupGlobals="false" backupStaticAttributes="false" beStrictAboutTestsThatDoNotTestAnything="true" beStrictAboutChangesToGlobalState="true" beStrictAboutOutputDuringTests="true" colors="true" convertErrorsToExceptions="true" convertNoticesToExceptions="true" convertWarningsToExceptions="true" processIsolation="false" stopOnFailure="false" bootstrap="tests/bootstrap.php">
+  <coverage processUncoveredFiles="true">
+    <include>
+      <directory suffix=".php">./src/</directory>
+    </include>
+  </coverage>
+  <testsuites>
+    <testsuite name="Test Suite">
+      <directory>./tests/</directory>
+    </testsuite>
+  </testsuites>
 </phpunit>
diff --git a/src/Infrastructure/Persistence/User/InMemoryUserRepository.php b/src/Infrastructure/Persistence/User/InMemoryUserRepository.php
index b85a74fa3..43976e61e 100644
--- a/src/Infrastructure/Persistence/User/InMemoryUserRepository.php
+++ b/src/Infrastructure/Persistence/User/InMemoryUserRepository.php
@@ -18,7 +18,7 @@ class InMemoryUserRepository implements UserRepository
     /**
      * @param User[]|null $users
      */
-    public function __construct(array $users = null)
+    public function __construct(array|null $users = null)
     {
         $this->users = $users ?? [
             1 => new User(1, 'bill.gates', 'Bill', 'Gates'),