1.21.10, shulker boxes, maybe no holos in 1.21.9, fixed a bug

• 1.21.10 support, holos maybe broken in 1.21.9, I hope you won't use this version or that it will be fixed later.
• Shulker boxes can now be used as chest type. All of them.
• Fixed a bug when creating a chest would throw a castException (if using a barrel to create the chest.)