fix(tests): Remove deprecated syntax

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

Author: susnux

tests/Listener/SetUserDefaultsTest.php

@@ -42,6 +42,16 @@ class SetUserDefaultsTest extends TestCase {
 	 */
 	private $listener;
 
+	/**
+	 * @var IUser|MockObject
+	 */
+	private $user;
+
+	/**
+	 * @var PostLoginEvent
+	 */
+	private $event;
+
 	public const UID = 'myuser';
 
 	public function setUp(): void {