Update Kafka version to 4.0

[scholzj]

Kafka has recently had a new major release 4.0. This PR updates the OPA Authorizer to use Kafka 4.0 as well:

• In the examples, it uses now the official Apache Kafka image and KRaft instead of ZooKeeper
• It uses Kafka 4.0 as a dependency. The code (mainly test code) is updated to handle different refactorings in Kafka classes (movements between packages etc.). It also updates the packaging as the recent Kafka version dropped some dependencies such as the Jackson Scala module which now need to be used as the OPA Authroizer dependency.

[anderseknert]

Hey Jakub, and thanks! Just got back from KubeCon with a hefty backlog 😅 Reviewing this is on my TODO list!

[scholzj]

No worries, it is not urgent. The current code works with Kafka 4.0. I just wanted to keep it a bit up to date.

[anderseknert]

Very nice! Just some questions but nothing blocking.

[anderseknert]

🎉

[anderseknert]

Is this still true? i.e. you can still drop this jar into a Kafka that old?

[scholzj]

Good point. The code itself is not really changed much. But the changes around Jackson dependencies make it compatible with Kafka 3.8 and newer (because of the Jackson versions it uses). I guess that should be fine as there are no real new feature here and users of older Kafka versions can use the previous release of the OPA Authorizer?

[anderseknert]

Yeah, fine with me 👍

[anderseknert]

Changes LGTM, feel free to merge whenever you want.