As the Template content type has been removed (no longer needed), you'll need to uninstall 1.x and reinstall 2.x. No official upgrade path is provided, but you may be able to delete the content type, and then update normally. This isn't supported, however.
Apply Details form type to title and argument options to prepare for advanced options module
Run codesniffer on code
Fixes to views plugin filter: https://www.drupal.org/node/2857697
Add error message for when no plugin available in a view
Add Empty validation on display_id value