Bug Fix: On WordPress 5.5, use the new auto-update notification instead of the debug email.
Bug Fix: Updated lib/updater to 1.6.4 Added support for the auto-update feature introduced in WordPress 5.5.
Bug Fix: Update lib/updater to the latest version. Fixed fatal error that can happen when upgrading to the 1.6.1 version of this code: Ithemes_Updater_Settings::get_licensed_site_url() in server.php:199".
