Fix crash with 1.20 smithing table

By: md_5 <git@md-5.net>

paper-server/src/main/java/org/bukkit/craftbukkit/event/CraftEventFactory.java

@@ -1484,7 +1484,7 @@ public class CraftEventFactory {
     public static PrepareSmithingEvent callPrepareSmithingEvent(InventoryView view, ItemStack item) {
         PrepareSmithingEvent event = new PrepareSmithingEvent(view, CraftItemStack.asCraftMirror(item).clone());
         event.getView().getPlayer().getServer().getPluginManager().callEvent(event);
-        event.getInventory().setItem(2, event.getResult());
+        event.getInventory().setResult(event.getResult());
         return event;
     }