Dropped support for the SkyBlockEarth plugin.

The SkyblockEarth plugin hook has been removed due to the actual unsureness and dramas created around the SkyblockEarth plugin.
There are rumors around that updates are still distributed on a third party website, but we can't support these versions since the API had become closed source.

For 1.13 users, I highly recommend using BentoBox. It is a pretty advanced SkyBlock plugin that is highly scalable because of its modularity.

This update includes:
- removed SkyblockEarth hook