Add empty line after access modifier

Rubocop was complaining about Layout/EmptyLinesAroundAccessModifier in
the tags controller.

This issue was introduced in commit e76735031. Unfortunately, it looks
like Pronto doesn't detect this issue because the access modifier was
already there; only the lines below it were introduced in that pull
request.

app/controllers/admin/tags_controller.rb

@@ -26,6 +26,7 @@ class Admin::TagsController < Admin::BaseController
   end
 
   private
+
     def tags
       @tags ||= Tag.category.page(params[:page])
     end