updating structure

rector.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+use Rector\Set\ValueObject\LevelSetList;
+use Rector\Set\ValueObject\DowngradeLevelSetList;
+
+return static function (RectorConfig $rectorConfig): void {
+    $rectorConfig->parallel();
+    $rectorConfig->cacheDirectory(__DIR__ . '/var/rector');
+    $rectorConfig->paths([
+        __DIR__ . '/src',
+        __DIR__ . '/tests',
+    ]);
+    $rectorConfig->sets([
+        LevelSetList::UP_TO_PHP_83,
+        // DowngradeLevelSetList::DOWN_TO_PHP_81,
+    ]);
+};