Close DB after each model generation

Each new app instance will open a new database connection, when generating a lot of models this causes a "Too many connections" error.

src/commands/BatchController.php

@@ -403,6 +403,7 @@ public function actionModels()
             $app = \Yii::$app;
             $temp = new \yii\console\Application($this->appConfig);
             $temp->runAction(ltrim($route, '/'), $params);
+            $temp->get($this->modelDb)->close();
             unset($temp);
             \Yii::$app = $app;
             \Yii::$app->log->logger->flush(true);