As long as the assets created allows commercial use (e.g. Donations are considered commercial since the developer gets monetary gain) and the judges and participants aren't required to pay, this should be fine.
Thanks, you guys will be able to tell the difference between pay what you like and pay right? Itch.io makes it looks like you have to pay as the button to not pay is tiny.
We can tell the difference, but to avoid confusion or making your entry less accessible to others, we suggest keeping it fully free during the voting period.