Make new page form wider

Some languages are very verbose, so we need more space for the parent page label

(cherry picked from commit d85fdce)

app/views/alchemy/admin/pages/_toolbar.html.erb

@@ -8,7 +8,7 @@
     tooltip_placement: "top-start",
     dialog_options: {
       title: Alchemy.t('Add a page'),
-      size: '340x215',
+      size: '420x215',
       overflow: true
     },
     label: Alchemy.t('Add a page'),