With #2013 we are moving to Jupiter for the integration test and using matrix builds for the tests.

Let's move everything to GitHub Actions for modelling more complex scenarios. We should have the following:

• Run and compile everything with JDK 8, 11, 13, 14-ea and 15-ea
• Compile processor with JDK 8 and run integration tests with 11, 13, 14-ea and 15-ea
• Publish SNAPSHOTs to Central
• Publish code coverage to codecov