Deprecate in favor of Field Group module

I'm not planning to work on a D10 compatible release anyway, as we haven't used this module for years (we also do not use field_group too). So let's do this :)

PS: feel free to provide a migration path to field_group. I'll push your changes, however won't work by myself on that for the mentioned reasons

@agoradesign thank you! I'm not using this module, just found it when searching for our bug causes... but it was field_group and I was confused that horizontal_tabs existed in two modules ;)

So if anyone needs it, he / she should provide the migration path.

afaik my module is only providing a form element, has nothing to do with fields or any other kind of config - so I guess there isn't anything to migrate at all

Automatically closed - issue fixed for 2 weeks with no activity.