add vorburger.exec & zt-exec

Hello @akullpp and awesome-java maintainers,

would you consider adding https://github.com/vorburger/ch.vorburger.exec ? FYI re. "popularity" of vorburger.exec don't look just at the stars on that repo - it's [used really widely indirectly through MariaDB4j](https://github.com/vorburger/MariaDB4j/).

and even the "competition" to (my) vorburger.exec, the https://github.com/zeroturnaround/zt-exec ? ;-) just FYI see also https://github.com/zeroturnaround/zt-exec/pull/25

FYI I'm the same guy from #465 (and #653) from a while ago.

Thanks for maintaining this!