Fix to turn mob spawning off when a drill incurs a malfunction (#3551)

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## About The Pull Request

This fix toggles fauna spawning off after a drill is beset by a
malfunction.

## Why It's Good For The Game

I've seen several instances of runaway spawning occurring after a drill
suffers a malfunction. When this happens, it cannot be toggled off by
alt-clicking on it, and it _must_ be unwrenched. This should fix that
behavior.

## Changelog

:cl:
fix: fixed fauna spawning after drill malfunctions
/:cl:

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code/modules/mining/drill.dm

@@ -344,6 +344,8 @@
 
 //Overly long proc to handle the unique properties for each malfunction type
 /obj/machinery/drill/proc/malfunction(malfunction_type)
+	if(active)
+		mining.toggle_spawning() //turns mob spawning off after a malfunction
 	switch(malfunction_type)
 		if(MALF_LASER)
 			say("Malfunction: Laser array damaged, please replace before continuing mining operations.")