Run action with Java 21

[sormuras]

Update to use pre-installed Java 21 to run actions via JAVA_HOME_21_X64 or JAVA_HOME_21_arm64.

• https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2004-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/ubuntu/Ubuntu2204-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/macos/macos-11-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/macos/macos-12-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/macos/macos-13-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/macos/macos-13-arm64-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/macos/macos-14-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/macos/macos-14-arm64-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/windows/Windows2019-Readme.md#java
• https://github.com/actions/runner-images/blob/main/images/windows/Windows2022-Readme.md#java