Merge pull request #79 from schrom01/feature_updaeTaskListViewOnUpdate_M3

update tasks with subscription from JsonTaskList

src/test/java/ch/zhaw/gartenverwaltung/io/JsonTaskListTest.java

@@ -130,7 +130,7 @@ public class JsonTaskListTest {
     }
 
     @Test
-    void testSubscription() {
+    void testSubscription() throws IOException {
         TaskList.TaskListObserver mockObs = Mockito.mock(TaskList.TaskListObserver.class);
         testDatabase.subscribe(mockObs);
         try {