Version 1.0.3 Vertical Tabs functionality is not compatible with Drupal 8

Problem/Motivation

The 1.0.3 release changes the classes used to turn node edit pages into vertical tabs. This is due to a change in how Drupal 9 outputs vertical tabs (See: https://www.drupal.org/project/claro_extras/issues/3211235). After upgrading from 1.0.2 to 1.0.3, edit pages no longer use vertical tabs and revert back to the two column layout.

Steps to reproduce

• Have a working Drupal 8 site.
• Install and enable version 1.0.2
• Enable the "Display block meta as vertical tabs" setting at /admin/appearance/settings/claro_extras
• Verify that a node edit page has been converted to a vertical tab layout
• Upgrade claro_extras to 1.0.3 and clear caches
• Go back to a node edit page and verify that the layout has reverted back to two columns

Proposed resolution

Since this is a breaking change for D8, I would recommend that you start a new branch for D9+ development, such as dev-2.x and then re-release the fix for D9 as v2.0.0.

That way, any future patches for D8 can be released on the dev-1.x branch and D9 patches can be released on dev-2.x. I realize this might cause efforts to be duplicated in order to patch both branches for fixes that apply to both versions.

Alternatively, if there is a way to programmatically determine which version of core is running on the site, there could be a conditional statement which sets the vertical tabs classes to use in the module.

Remaining tasks

• Re-release changes from 1.0.3 as 2.0.0
• Update module description page to explain the difference between the two branches