Iron's Spellbooks loot fixes

A small datapack that makes some changes to a few vanilla loot tables for a slightly better experience with Iron's Spells 'n Spellbooks. It will remove redundant loot from mobs and make a few small changes to other loot tables.

These are the only changes that are made:

• Removed bones from strays loot, so they only drop frozen bones
• Removed leather from hoglin loot, so they only drop hogskin
• Replaced leather with hogskin in bastion chests
• Removed potatoes and carrots from zombies loot table, added poisonous potato instead (rare by default)

Datapacks need to be placed inside the 'datapacks' folder found in your worlds 'save' file. Alternatively, load datapacks globally with a mod like Paxi or Global Packs.