Converting Jenkins CI system into Github actions

[Rene Gassmoeller]

CIG is planning to transition away from its self-hosted Jenkins continuous integration system to a cloud solution (preferentially Github actions). The benefits of the new system are that they are independent from CIG hardware, and are automatically updated by Github. This means for example before the currently used Ubuntu version reaches its end of support the CI infrastructure will be automatically migrated to a newer Ubuntu version. CIG will still provide support to its packages for updating/improving the scripts. The interface to the new test results looks as follows: https://github.com/gassmoeller/conman/actions

Is this something the Selen developers would be fine with moving forward? We think this is the objectively better solution, but are happy about feedback. I could easily transfer the Jenkinsfile in the current repository into a configuration file for Github actions. We can also discuss alternatives.