Test Julia LTS and stable version

[AnHeuermann]

The Jenkinsfile is using docker.openmodelica.org/omjulia-build-deps:v0.1.0 where Julia v1.0.3 is installed.
The current LTS (1.6.7) and stable (v1.8.2) versions should also be tested.

Both could be added to the Dockerfile and two more stages can be added to the Jenkins pipeline. But then someone has to keep track of what is the current stable / LTS version and update the Jenkinsfile.

It is also possible to use a GitHub workflow on a Docker image with OpenModelica and add the setup-julia action to it.