Smart metal foam fixes multi-z holes (#92050)

## About The Pull Request
Smart metal foam places foam plating on openspace

## Why It's Good For The Game
It's supposed to fill the room but it leaves a bunch of holes to fall in

## Changelog

🆑 Melbert
qol: Smart metal foam fixes multi-z holes
/🆑

code/game/objects/effects/effect_system/fluid_spread/effects_foam.dm

@@ -401,7 +401,7 @@
 
 /obj/effect/particle_effect/fluid/foam/metal/smart/make_result() //Smart foam adheres to area borders for walls
 	var/turf/open/location = loc
-	if(isspaceturf(location))
+	if(isspaceturf(location) || isopenspaceturf(location))
 		location.place_on_top(/turf/open/floor/plating/foam)
 
 	for(var/cardinal in GLOB.cardinals)