refactor: PHP 8 features

src/Plugins/Environment.php

@@ -21,17 +21,10 @@ final class Environment implements HandlesArguments
      */
     public const LOCAL = 'local';
 
-    /**
-     * @var \Pest\Plugins\Environment|null
-     */
-    private static $instance;
-
     /**
      * The current environment.
-     *
-     * @var string|null
      */
-    private static $name;
+    private static ?string $name = null;
 
     /**
      * Allows to handle custom command line arguments.