If you were active on the server, you would know by just going to /shop that there's a sign explaining that shop signs are broken because we are still trying to find time to update essentials to 1.13.
So, before suggesting 1.13 items to shop and sell, maybe wait for the plugin to update on the server, please? We can't do impossible things and jump over an update on a step by step process. Seems a very innoportune request at this moment.