I've got a data.frame with lats and lngs that define the boundaries of rectangular boxes, like so
geohash north_lat south_lat east_lng west_lng
1 gbsuv 48.69141 48.64746 -4.306641 -4.350586
2 gbsuy 48.69141 48.64746 -4.262695 -4.306641
What's the easiest way to convert this into an sf object that holds a column of POLYGONs?