Move to akka 2.12.7.

- Required due to the similar update in apache/openwhisk.

Author: falkzoll

settings.gradle

@@ -10,11 +10,15 @@ gradle.ext.openwhisk = [
 ]
 
 gradle.ext.scala = [
-    version: '2.13.6',
+    version: '2.12.7',
+    depVersion  : '2.12',
     compileFlags: ['-feature', '-unchecked', '-deprecation', '-Xfatal-warnings', '-Ywarn-unused-import']
 ]
 
 gradle.ext.scalafmt = [
     version: '1.5.0',
     config: new File(rootProject.projectDir, '.scalafmt.conf')
 ]
+
+gradle.ext.akka = [version : '2.6.12']
+gradle.ext.akka_http = [version : '10.2.4']

tests/build.gradle

@@ -69,6 +69,15 @@ dependencies {
     compile "org.scala-lang:scala-library:${gradle.scala.version}"
     compile "org.apache.openwhisk:openwhisk-tests:${gradle.openwhisk.version}:tests"
     compile "org.apache.openwhisk:openwhisk-tests:${gradle.openwhisk.version}:test-sources"
+    implementation group: 'com.typesafe.akka', name: "akka-http2-support_${gradle.scala.depVersion}", version: "${gradle.akka_http.version}"
+    implementation group: 'com.typesafe.akka', name: "akka-http-xml_${gradle.scala.depVersion}", version: "${gradle.akka_http.version}"
+    implementation group: 'com.typesafe.akka', name: "akka-discovery_${gradle.scala.depVersion}", version: "${gradle.akka.version}"
+    implementation group: 'com.typesafe.akka', name: "akka-protobuf_${gradle.scala.depVersion}", version: "${gradle.akka.version}"
+    implementation group: 'com.typesafe.akka', name: "akka-remote_${gradle.scala.depVersion}", version: "${gradle.akka.version}"
+    implementation group: 'com.typesafe.akka', name: "akka-cluster-metrics_${gradle.scala.depVersion}", version: "${gradle.akka.version}"
+    implementation group: 'com.typesafe.akka', name: "akka-cluster_${gradle.scala.depVersion}", version: "${gradle.akka.version}"
+    implementation group: 'com.typesafe.akka', name: "akka-cluster-tools_${gradle.scala.depVersion}", version: "${gradle.akka.version}"
+    implementation group: 'com.typesafe.akka', name: "akka-distributed-data_${gradle.scala.depVersion}", version: "${gradle.akka.version}"
 }
 
 tasks.withType(ScalaCompile) {