- build using Java 20 (use toolchain because Gradle 8.1.1 does not support running and compiling on Java 20 because Kotlin does not support 20 as target version)
- use temurin distribution as default because it is pre-installed on ubuntu-latest
- use actions/setup-java@v2 (provides caching gradle files)
- use pre-installed Java 8 and 11
- no longer build on Java 9 and 14
- not yet build on Java 17 because used Gradle version 6.8.2 does not support it
can not yet upgrade to Gradle 7.x because nokee plugins (for C++) does not support it