apply rector rules: php up to php82

docs/source/development/user-interface/widgets/ChillMainConfiguration.php

@@ -25,7 +25,7 @@ class ChillMainConfiguration implements ConfigurationInterface
 
     public function __construct(
         array $widgetFactories,
-        private ContainerBuilder $containerBuilder
+        private readonly ContainerBuilder $containerBuilder
     ) {
         // we register here widget factories (see below)
         $this->setWidgetFactories($widgetFactories);