Absolutely anything you want. I wore something semi-casual. Some people wore hoodies, some wore suits. It absolutely doesn't matter. Is your interview online or in-person? If it's online, even more reason to wear whatever you want so long as there is no propaganda or anything else of the sort.
If it's in person, I'd be slightly more careful but it doesn't matter too much. At the end of the day, it's what you say in the interview that matters so what you wear will not be taken into account too much.