Add void return to method in tests. (#20602)

tests/framework/rbac/MySQLManagerCacheTest.php

@@ -8,6 +8,7 @@
 
 namespace yiiunit\framework\rbac;
 
+use yii\rbac\ManagerInterface;
 use yii\caching\FileCache;
 use yii\rbac\DbManager;
 
@@ -20,7 +21,7 @@ use yii\rbac\DbManager;
 class MySQLManagerCacheTest extends MySQLManagerTest
 {
     /**
-     * @return \yii\rbac\ManagerInterface
+     * @return ManagerInterface
      */
     protected function createManager()
     {