Feverfew Fix (vgstation-coders#35922)

Changes the metabolism of Feverfew to 0.2 so one cactus prick no longer lasts 10 minutes.

code/modules/reagents/reagents/reagents_medical.dm

@@ -158,6 +158,7 @@
 	id = FEVERFEW
 	description = "Feverfew is a natural anticoagulant useful in fending off viruses, but it leaves one vulnerable to pain and bleeding."
 	color = "#b5651d"
+	custom_metabolism = 0.2
 	pain_resistance = -25
 	data = list ("threshold" = 80)