Make rubber leaves yield rubber leaves

Previously, you wouldn't get any leaves items from mining rubber tree leaves.
Leafdecay still doesn't drop the leaves, only the saplings, just like with normal trees.

technic_worldgen/rubber.lua

@@ -48,7 +48,11 @@ minetest.register_node(":moretrees:rubber_tree_leaves", {
 		items = {{
 			items = {"moretrees:rubber_tree_sapling"},
 			rarity = 20,
-		}}
+		},
+		{
+			items = {"moretrees:rubber_tree_leaves"},
+		}
+		}
 	},
 	sounds = default.node_sound_leaves_defaults(),
 })