The Events Calendar - Event Tickets Plus 6.3.0

* Tweak - Add going/not-going status while adding RSVP attendees manually. [ETP-706]
* Tweak - Refactored CSS for Tickets Emails to better conform to email client CSS standards. [ETP-872]
* Fix - The Attendee List will now be correctly displayed when the 'Show attendees list on event page' option is enabled within the classic editor. [ETP-623]
* Language - 0 new strings added, 1 updated, 0 fuzzied, and 0 obsoleted

* Fix - Addressed an issue where the system would provide duplicate plugin names when encountering an invalid license key. [ET-1738]
* Language - 0 new strings added, 24 updated, 0 fuzzied, and 0 obsoleted

* Version - Event Tickets Plus 5.7.1 is only compatible with Event Tickets 5.6.1 and higher.
* Fix - Lock our container usage(s) to the new Service_Provider contract in tribe-common. This prevents conflicts and potential fatals with other plugins that use a di52 container.