As someone who has been on "the other side" of interviewing people quite often (meaning I interviewed them): Don't forget, that they are positive towards you. They invited you to an interview because they are interested in you and your skills that are relevant for the job. Talking fluently is (in many jobs) not as relevant as we think. They know that as well. So if you want to slip in that you stutter at the beginning of the interview ("so that you don't interpret my stutter as insecurity or lack of knowledge"), go ahead. Keep us posted how it went. You can do this!