fix nether package typo

reported in https://github.com/minetest-mods/3d_armor/issues/66

3d_armor/mod.conf

@@ -1,4 +1,4 @@
 name = 3d_armor
 depends = default
-optional_depends = player_monoids, armor_monoid, pova, fire, ethereal, bakedclay, moreores, ether
+optional_depends = player_monoids, armor_monoid, pova, fire, ethereal, bakedclay, moreores, nether
 description = Adds craftable armor that is visible to other players.