+ When changing most gui items, you can add a custom model number to the material name. Example: GOLD_INGOT:5 will use a custom model data of 5.
+ Run AuctionBidEvent async though main auction menu
+ Extracted listing requirements for items. Ex. Added the requirement check to both bin/auction sell menus.
+ Fixed bug where sell menus would ignore the listing cooldown

(!) I'll keep saying it, I highly suggest updating to 1.16+ as any support / compatibility for anything below that is being completely dropped this year. This goes for all my plugins that haven't done so already.