Fix CI

Author: Malax

test/compile_test.sh

@@ -28,6 +28,10 @@ EOF
 
   cat > ${projectRoot}/build.sbt <<EOF
 TaskKey[Unit]("stage") in Compile := { println("${SBT_STAGING_STRING}") }
+EOF
+
+  cat > ${projectRoot}/system.properties <<EOF
+java.runtime.version = 8
 EOF
 
   mkdir -p ${projectRoot}/project