test: use valid syntax in valid phhp 8.1 class

tests/ValidPhp81Class.php

 <?php
 
-use N\{ClassName,
-    AnotherClassName,
-    OneMoreClassName
-};
+namespace A {
 
-$instance = new class {
-};
+    use N\{ClassName,
+        AnotherClassName,
+        OneMoreClassName
+    };
 
-namespace A {
+    $instance = new class {
+    };
 
     #[Attribute] #[Attribute(1, 2)] function foo()
     {
@@ -94,7 +94,7 @@ namespace A {
             "five",
             "six"
         );
-        var $v = 0; // comment 
+        var $v = 0; // comment
         public $path = "root"; // comment
 
         const FIRST = 'first';