Drupal 9 compatibility

It is not. Checked with module upgrade_status (screenshot added). Also started a patch that fixes the core_version_requirement and replaced the dependency on jquery.ui_sortable with core/sortable. This will break sorting because autcomplete_deluxe.js still needs an update to fix the deprecated sortable function and replace it with the new core alternative.

Reference : https://www.drupal.org/node/3084730

Woops! I misinterpreted the warning about jquery.ui_sortable. The core usages are removed, not the library itself. So this will only give a deprecation notice. EDIT this is wrong

Added a new patch that only adds the core_version_requirement.

Been watching too many change records and crossed my wired. I was right in the #2

As stated in https://www.drupal.org/node/3084730
The core/jquery.ui.sortable library is deprecated in Drupal 8.8 and is removed from Drupal 9.

So jquery.ui_sortable still needs to be replaced with core/sortable and the JS code needs to be updated.

We could add https://www.drupal.org/project/jquery_ui_sortable as temporary replacement so we don't have to fix the JS code, but I will leave this for the maintainer to decide how to proceed.

Presuming this is for Drupal 9 porting weekend since this was worked on during that time.

#7 Passes tests with Upgrade Status module

Committed ... Thanks all :)