Formspec now updates after applying enchantment

* This prevents crash when trying to apply a second enchantment
* backported 556d978708

src/enchanting.lua

@@ -123,6 +123,7 @@ function enchanting.fields(pos, _, fields, sender)
 		inv:set_stack("mese", 1, mese)
 		inv:set_stack("tool", 1, tool)
 	end
+	enchanting.formspec(pos)
 end
 
 function enchanting.dig(pos)