Update tests/ActiveFixtureTest.php

Co-authored-by: Alexander Makarov <sam@rmcreative.ru>

Author: ziaratban

tests/ActiveFixtureTest.php

@@ -147,7 +147,7 @@ class {$className} extends \yii\mongodb\ActiveFixture
 
         $fixture = new $className([
             'collectionName' => [
-                yii::$app->mongodb->getDefaultDatabaseName(),
+                Yii::$app->mongodb->getDefaultDatabaseName(),
                 Customer::collectionName()
             ],
         ]);