Set group for test tasks

We want to make them visible to users. This makes it more obvious to
them that it's possible to only run the tests using one of the
simulators and that they don't have to run the `check` task which tries
to run with both.

src/main/java/com/verificationgentleman/gradle/hdvl/svunit/SVUnitPlugin.java

@@ -33,6 +33,7 @@
 import org.gradle.api.internal.HasConvention;
 import org.gradle.api.reflect.TypeOf;
 import org.gradle.api.tasks.TaskProvider;
+import org.gradle.language.base.plugins.LifecycleBasePlugin;
 import org.gradle.util.GUtil;
 
 import java.io.File;
@@ -134,6 +135,7 @@ private void configureTestTask(Project project, SourceSet mainSourceSet, SourceS
         TaskProvider<TestTask> testTask = project.getTasks().register(Names.getTestTaskName(toolName), TestTask.class, new Action<TestTask>() {
             @Override
             public void execute(TestTask testTask) {
+                testTask.setGroup(LifecycleBasePlugin.VERIFICATION_GROUP);
                 testTask.setDescription("Runs the unit tests using SVUnit.");
                 testTask.getToolName().set(toolName.toLowerCase());
                 testTask.getMainArgsFile().set(genFullArgsFile.getDestination());