Fix #20513: Fix code examples in PHPDoc

framework/web/UrlNormalizer.php

@@ -57,7 +57,7 @@ class UrlNormalizer extends BaseObject
      * - `404` - [[NotFoundHttpException]] will be thrown
      * - `callable` - custom user callback, for example:
      *
-     *   ```php
+     *   ```
      *   function ($route, $normalizer) {
      *       // use custom action for redirections
      *       $route[1]['oldRoute'] = $route[0];