It's an easy fold. This player is playing their hand face-up. They checked OOP on every street and then check-raised on the river with a potential flush on board. I find this spot so often that I often won't value bet on the river when either the board pairs or there's a flush and many times they'll turn up a made hand that beats what I have. Or, if I bet, I will bet smaller.
So many people are playing their hands face up at the micro stakes, though with the nut blocker, I like the value bet, though I'd have bet out smaller, say about 22-27 cents. But at least you can note this about this player and seeing that you're playing full ring (non-Zoom), you can exploit how they play these draws in the future.