Update JDK action workflow matrix with JDK 16.0.0-ea.24

As seen https://github.com/debezium/debezium/runs/1427204063?check_suite_focus=true

The workflow attempts to download JDK 16.0.0-ea.20 but this EA release no longer there, so we need to upgrade to the ea.24 release of JDK 16.