Update _Deep_Forest.dmm (#4942)

Removes the last mine that Elk missed when clearing up the excel outpost. The one that has been making our tests fail for months and that I till now have been too lazy to remove.

maps/_DeepForest/map/_Deep_Forest.dmm

@@ -11678,10 +11678,8 @@
 /area/nadezhda/dungeon/outside/prepper/vault/floor2)
 "koI" = (
 /obj/random/junk,
-/obj/item/mine/excelsior{
-	armed = 1
-	},
 /obj/item/ammo_casing,
+/obj/item/mine/armed,
 /turf/simulated/floor/tiled/dark/brown_platform,
 /area/nadezhda/dungeon/outside/prepper/vault{
 	narrate = "A great, massive structure. Rotting and decayed, though seemingly maintained to some minimum, the whole vault feels as if it could collapse around you at any moment, the shuffling of steel-clad boots echoes through the halls.";