Update license: MIT → Apache 2.0

[Renset]

The MIT license is great for small libraries or packages because of how permissive it is, but for a full application, it feels a bit too open. Apache 2.0 still gives plenty of freedom but strikes a better balance, offering more protection for both the project and its contributors. So I decided to use Apache 2.0 in further versions of macai (starting from v2.0.0)