The primary change in this release is dropping database synchronization of entitlements.
The Entitlement class is no longer an instance of an Eloquent model.
The static has method operates with the same behavior in a backwards compatible manner,
so no changes to code will be necessary there to upgrade.
If you never used the entitlement tables, then a clean upgrade would drop those tables.
Secondly, legacy configuration mappers from versions 1 and 2 have been removed.
If you are using an old config file, then you need to publish the vendor file and update attributes accordingly.