[docs] CoreExtension::setEscaper is deprecated

doc/filters/escape.rst

@@ -100,7 +100,7 @@ used in the ``escape`` call) and the second one must be a valid PHP callable:
 .. code-block:: php
 
     $twig = new \Twig\Environment($loader);
-    $twig->getExtension(\Twig\Extension\CoreExtension::class)->setEscaper('csv', 'csv_escaper');
+    $twig->getExtension(\Twig\Extension\EscaperExtension::class)->setEscaper('csv', 'csv_escaper');
 
 When called by Twig, the callable receives the Twig environment instance, the
 string to escape, and the charset.