testing/openjdk20: new aport
This MR adds OpenJDK20, the latest release of java.
We are currently working on getting Alpine Linux 3.21 out. This means that merge requests that are not aimed to help with that (only affecting testing, new aports) have a lower priority at the moment. Please be patient, they will be eventually picked up.
This MR adds OpenJDK20, the latest release of java.