Removes the level 39 xp cost limit in anvils.

This mod still partially works when only present on one side
- Server side: removes the level limit
- Client side: correctly displays the xp cost instead of saying "TOO EXPENSIVE" but is not required for the core functionality

Can also fix the anvil text if playing on a vanilla-compatible Fabric server with AnvilFix, or possibly other Fabric mods that remove the xp limit.

NOTE: renaming an item will still cost at most 39 levels

Please create an issue if you find a scenario where the incorrect text is shown in an anvil, or would like compatability with another mod.