Forgejo changes license to GPLv3+

The Forgejo project has announced that, starting from version 9.0, Forgejo will be released under the GPLv3 license (or a later version). Older versions of the software forge remain MIT-licensed.

A copyleft license makes reusing other copyleft software easier. Recently, we discovered that some of the dependencies we used were incompatible with the license Forgejo was distributed with, and they had to be removed for now. Choosing copyleft licenses enables us to reuse more work, and saves us precious time to focus on improving Forgejo itself.