message: Fix missing async in saveTask
  When working with the tutorial I get the error, that "await" can only be used inside an async function.
  When introducing the saveTask-function the async is missing. This should fix it.
diff: @@ -58,7 +58,7 @@ function App() {
  setTasks(tasks.map(t => t === task ? { ...task, ...values } : t));
  };
  - const saveTask = () => {
  + const saveTask = async () => {
  const savedTask = await taskRepo.save(task);
  setTasks(tasks.map(t => t === task ? savedTask : t));
  };
  @@ -114,7 +114,7 @@ function App() {
  setTasks(tasks.map(t => t === task ? { ...task, ...values } : t));
  };
  - const saveTask = () => {
  + const saveTask = async () => {
  const savedTask = await taskRepo.save(task);
  setTasks(tasks.map(t => t === task ? savedTask : t));
  };
  