Migrate to readonly properties

rector.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 use Rector\Config\RectorConfig;
 use Rector\Php80\Rector\Class_\ClassPropertyAssignToConstructorPromotionRector;
+use Rector\Php81\Rector\Property\ReadOnlyPropertyRector;
 
 return RectorConfig::configure()
     ->withPaths([
@@ -18,6 +19,9 @@ return RectorConfig::configure()
     ->withConfiguredRule(ClassPropertyAssignToConstructorPromotionRector::class, [
         'inline_public' => true,
     ])
+    ->withRules([
+        ReadOnlyPropertyRector::class,
+    ])
     ->withSkip([
         ClassPropertyAssignToConstructorPromotionRector::class => [
             __DIR__ . '/src/Entity/*',