build: add Rector

rector.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Core\Configuration\Option;
+use Rector\Set\ValueObject\SetList;
+use Rector\Set\ValueObject\DowngradeSetList;
+use Rector\Core\ValueObject\PhpVersion;
+use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
+
+return static function (ContainerConfigurator $containerConfigurator): void {
+    // get parameters
+    $parameters = $containerConfigurator->parameters();
+    
+    $parameters->set(Option::PATHS, [
+        __DIR__ . '/src',
+    ]);
+
+    // Define what rule sets will be applied
+    $parameters->set(Option::SETS, [
+       // SetList::CODE_QUALITY,
+        SetList::DEAD_CODE,
+       // DowngradeSetList::PHP_80,
+       // DowngradeSetList::PHP_74,
+       // DowngradeSetList::PHP_73,
+        //DowngradeSetList::PHP_72,
+    ]);
+
+    $parameters->set(Option::PHP_VERSION_FEATURES, PhpVersion::PHP_71);
+};