Merge pull request #93 from mkurz/no_nashorn_java_17

Java 15 dropped the Nashorn JavaScript Engine, can't run tests with 17

Author: mkurz

src/test/scala/com/typesafe/sbt/jse/engines/JavaxEngineSpec.scala

@@ -6,6 +6,8 @@ import scala.collection.immutable
 
 class JavaxEngineSpec extends Specification {
 
+  args(skipAll = !(sys.props("java.specification.version") == "1.8" || sys.props("java.specification.version") == "11"))
+
   "A JavaxEngine" should {
 
     "execute some javascript by passing in a string arg and comparing its return value" in {