Fixes scanner icon setting (#2479)

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## About The Pull Request
the scanner machine updates its icon now
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## Why It's Good For The Game
player feedback
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## Changelog

:cl:
fix: The polymodial sensor array now properly changes icon_state. 
/:cl:

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code/modules/overmap/missions/research_mission.dm

@@ -129,7 +129,7 @@
 		use_power = NO_POWER_USE
 	power_change() // calls update_appearance(), makes sure we're powered
 
-/obj/machinery/mission_scanner/update_icon_state()
+/obj/machinery/mission_scanner/update_appearance(updates)
 	. = ..()
 	if(is_operational)
 		icon_state = "scanner_power"