[BUG] AppImage file not building

[Rek9876boss]

Environment (please complete the following information):

• Program version: 1.0.3

Describe the bug
'mvn clean package' does not build AppImage on linux

Explain Steps To Reproduce

1. run 'mvn clean package' in source folder

Expected behavior
AppImage file created

Additional context
Issue caused by update to AppImage releases method, see: https://github.com/AppImage/AppImageKit/releases/

Javapackager not updated to account for continuous release.
Pull request fixing this issue to be found here: javapackager/JavaPackager#481