2.0.0-beta.13 for 1.21

Tweaked mechanics for the Acolyte's Bindings. (@enjarai)
- They now use a hidden sixth spell slot that can't be directly cancelled.
Fixed bugs. (@enjarai)
- Levitating blocks were dropping themselves as items when entering the void.
- Levitating blocks were losing data when unloaded.
- Levitating blocks could be created from fluids.
- Swap block and featherweight were dropping the contents of ungenerated loot table blocks.