Java 11 base image

[renjfk]

Hi,

Is there any reason why the base image is Java 11? The latest Java LTS is Java 21 and it outperforms Java 11 in every aspect so it's a bit wasteful for it to be Java 11.

[Syer10]

I haven't gotten around to updating the base image, as long as the PR tests pass it would likely work out of the box though

[renjfk]

This is probably out of context, but even though the project is scaled really small, it would be much better if the container image was built with Jib, as it integrates perfectly with Gradle and outputs really optimized images (e.g. almost half the size compared to what Docker builds) for Java applications.