Help with updating Formbuilder-rb Gemspec to support Rails 5.

I’ve been searching everywhere for a proper drag and drop solution for my rails forms. I came across FormBuilder-rb which is supported by Formbuilder.js. The gem currently doesn’t support Rails 5, because it’s unmaintained and it also doesn’t work with MySQL (Only Postgres) Can you give me a hand in modernizing the gem for Rails 5? I really need this feature, badly.