add api-version line

[AeSix]

This is needed to prevent CratesPlus from operating in compatibility mode. All item names must use new material names before this can be accepted.

Spigot's built-in compatibility transformers are not efficient and should not be used. As CP 5.x is intended for 1.14.x+ this line should be added. If CP uses old item names, this WILL cause the plugin to fail.

Github made the line 15 -> 16 change noted here.