⬆️ Upgrade lib : nikic/php-parser

We were on v3 that is no longer maintained and compatibility is annonced for PHP 7.2.
v4 is active and supports PHP up to 8.0
No problem to update as this is only used in the config editor (\Combodo\iTop\Config\Validator\iTopConfigAstValidator)

lib/nikic/php-parser/lib/PhpParser/NodeVisitorAbstract.php

@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 namespace PhpParser;
 
@@ -7,8 +7,19 @@ namespace PhpParser;
  */
 class NodeVisitorAbstract implements NodeVisitor
 {
-    public function beforeTraverse(array $nodes)    { }
-    public function enterNode(Node $node) { }
-    public function leaveNode(Node $node) { }
-    public function afterTraverse(array $nodes)     { }
-}
+    public function beforeTraverse(array $nodes) {
+        return null;
+    }
+
+    public function enterNode(Node $node) {
+        return null;
+    }
+
+    public function leaveNode(Node $node) {
+        return null;
+    }
+
+    public function afterTraverse(array $nodes) {
+        return null;
+    }
+}