1.21.11+ item atlas should be in atlases/items.json, rather than atlases/blocks.json (old).

Hey I think I might have found an issue (although it might be in my config) regarding MythicCrucible pack generation.

in: assets/minecraft/atlases/blocks.json

  "sources": [
    {
      "source": "entity",
      "prefix": "entity/",
      "type": "directory"
    },
    {
      "source": "armor",
      "prefix": "armor/",
      "type": "directory"
    },
    {
      "source": "item",
      "prefix": "item/",
      "type": "directory"
    }
  ]
}```

is generated, however in newer versions (1.21.11+):
```{
  "source": "item",
  "prefix": "item/",
  "type": "directory"
}```

should be generated in the items atlas rather than the blocks atlas.

If I now automatically merge this mythiccrucible generated pack into my CraftEngine generated pack it just breaks the armor component (models and texture will not work)
due to a double reference from both items (which it should be in) and blocks atlases. Could this artifact, which probably remained from older minecraft versions, be looked into?

Using newest dev versions of:
- `MythicCrucible-5.12.0`
- `MythicMobsPremium-5.12.1-SNAPSHOT`


Removing the:
```{
  "source": "item",
  "prefix": "item/",
  "type": "directory"
}```

from blocks atlas solves the issue.