Maven central moving to new publishing model and plugin

[bitwiseman]

It looks like Sonatype is moving to a new model for publishing:
sonatype/nexus-public#110 (comment)

The project may need to re-register or do some other updates to work in the new system:
https://central.sonatype.org/register/central-portal/
https://central.sonatype.org/publish/publish-portal-maven/

It is still in preview, so this is not urgent. I've started work on this but don't have time to finish it now:
https://github.com/hub4j/github-api/tree/feature/new-maven-central-publishing

[bitwiseman]

Had to update URLs: 7a06759

Not sure if there's more to be done here.

[bitwiseman]

Turns out this was not needed. Reversed. May want to migrate to central eventually, but not currently required.