Java 21 Support
(Similar to #233 (closed) "Java 17 Support")
Java 21 is an LTS release. Let's enable Java 21 in CI in addition to Java 11 and 21.
(Similar to #233 (closed) "Java 17 Support")
Java 21 is an LTS release. Let's enable Java 21 in CI in addition to Java 11 and 21.