Fix pager

I get this when trying to enable the dev version of the module with this patch applied:

The service "sites_simple_sitemap.service" has a dependency on a non-existent service "plugin.manager.site". Did you mean one of these: "plugin.manager.block", "plugin.manager.archiver", "plugin.manager.action", "plugin.manager.mail", "plugin.manager.sdc", "plugin.manager.editor", "plugin.manager.filter", "plugin.manager.search"?

The module successfully installs despite the error, but the error prevents any drush commands from completing.

I get the same result when trying to patch the alpha version.

Our customer tested this successfully.

@bhogue, Which version of sites do you use?