Removes Floor tiles under catwalks on the Mudskipper (#4019)

## About The Pull Request



## Why It's Good For The Game

Accidentally did this and Forgot to fix it

## Changelog

:cl:
fix: Fixes plating under some catwalks that aren't supposed to be there
on the Mudskipper
/:cl:

---------

Co-authored-by: github-actions <action@github.com>

_maps/shuttles/independent/independent_mudskipper.dmm

@@ -228,7 +228,7 @@
 	dir = 10
 	},
 /obj/structure/catwalk/over/plated_catwalk/dark,
-/turf/open/floor/plasteel/dark,
+/turf/open/floor/plating,
 /area/ship/engineering/engine)
 "eu" = (
 /obj/structure/railing{
@@ -710,7 +710,7 @@
 	icon_state = "2-5"
 	},
 /obj/structure/catwalk/over/plated_catwalk/dark,
-/turf/open/floor/plasteel/dark,
+/turf/open/floor/plating,
 /area/ship/engineering/engine)
 "qN" = (
 /obj/machinery/cryopod{
@@ -1460,7 +1460,7 @@
 	icon_state = "2-4"
 	},
 /obj/structure/catwalk/over/plated_catwalk/dark,
-/turf/open/floor/plasteel/dark,
+/turf/open/floor/plating,
 /area/ship/engineering/engine)
 "Id" = (
 /obj/effect/decal/cleanable/dirt/dust,