add bone drop to cow

cow.lua

@@ -30,6 +30,7 @@ mobs:register_mob("mobs_animal:cow", {
 	drops = {
 		{name = "mobs:meat_raw", chance = 1, min = 1, max = 3},
 		{name = "mobs:leather", chance = 1, min = 1, max = 2},
+		{name = "ethereal:bone", chance = 2, min = 2, max = 6}
 	},
 	water_damage = 1,
 	lava_damage = 5,