Fixes explosive implants (#6886)

# About the pull request
Closes #6873 
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# Explain why it's good for the game
Fix bugs
Better game
???
Profit
# Testing Photographs and Procedure
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# Changelog
:cl:
fix: Fixed explosive implant not triggering when hearing the code-word.
/:cl:

code/game/objects/items/implants/implant.dm

@@ -140,6 +140,7 @@ Implant Specifics:<BR>"}
 	var/elevel = "Localized Limb"
 	var/phrase = "supercalifragilisticexpialidocious"
 	icon_state = "implant_evil"
+	flags_atom = USES_HEARING
 
 /obj/item/implant/explosive/get_data()
 	var/dat = {"