I always let my interviewers know at the beginning of the interview that I have a stutter. I know no matter how well prepared I am, I am still going to stutter because it's not something I can control so the best I can do is to let them know in advance so that they are aware. You should let them know that you stutter and that is something you cannot control, you can also mention how your stutter manifests ( blocks, repetitions, etc...) so that they know what to expect and if they are decent people, they won't hold it against you. I have done it and I managed to secure internships/jobs. Good luck on your interview!!!