Add 'listing expired' alerts to LooksRare Discord Alert Bot (TM)#117

Currently there is no notification that happens when one of my listings on LR expires. With multiple wallets and collections, I sometimes miss items to relist. If I’m not alone, this means that oftentimes there is less liquidity in collections, and providing clear notifications when listing expire would help fix that.

I propose adding ‘listing expired’ notifications to the discord bot!