Update to Minecraft 1.21.6

• also works in Minecraft 1.21.5

Add "ash" clouds (normal clouds in the nether at y=102

• clouds don't exist when using Minecraft 1.21.5

Moved the dnt compat datapack to a overlay. To activate open the pack.mcmeta file in the zip/jar and edit line 27 from "formats": 0, to "formats": [0, 1000],.