How to add bootstrap-select to rails 5 app with bootstrap v5?

Question

Ruby on Rails

Migration from bootstrap v4 to v5 is in progress. Bootstrap-select stopped working, started searching and found that for bootstrap v5 bootstrap-select is just being developed. But it should already work with it, in theory, there is a commit called "support Bootsrap 5".

But after adding it still error:

Uncaught TypeError: Cannot read property 'Constructor' of undefined

When trying to do this in application.js:

jQuery.fn.modal.Constructor.Default.backdrop = 'static';

jQuery.fn.modal - undefined at the time of code execution. How can this be corrected?