fix test target by excluding testng dependency

core/build.gradle

@@ -25,6 +25,10 @@ configurations {
     }
 }
 
+configurations.testImplementation {
+        exclude group:'org.codehaus.groovy', module:'groovy-testng'
+}
+
 // publish core to local maven repo for sister projects
 publishing {
     publications {

host-cache/build.gradle

@@ -8,3 +8,7 @@ dependencies {
     testCompile 'junit:junit:4.12'
     testCompile "org.codehaus.groovy:groovy-all:${groovyVersion}"
 }
+
+configurations.testImplementation {
+        exclude group:'org.codehaus.groovy', module:'groovy-testng'
+}