message: Add observe on main thread in Timeline view
diff: @@ -18,13 +18,7 @@ namespace TogglDesktop
  private CompositeDisposable _disposable;
  public TimelineViewModel ViewModel
  {
  - get
  - {
  - if (Dispatcher.CheckAccess())
  - return DataContext as TimelineViewModel;
  -
  - return Dispatcher.Invoke(() => ViewModel);
  - }
  + get => DataContext as TimelineViewModel;
  set => DataContext = value;
  }
  @@ -42,6 +36,7 @@ namespace TogglDesktop
  _disposable = new CompositeDisposable();
  ViewModel?.WhenAnyValue(x => x.SelectedScaleMode).Buffer(2, 1)
  + .ObserveOn(RxApp.MainThreadScheduler)
  .Select(b => (double)TimelineViewModel.ScaleModes[b[1]] / TimelineViewModel.ScaleModes[b[0]])
  .Subscribe(ratio => SetMainViewScrollOffset(MainViewScroll.VerticalOffset * ratio))
  .DisposeWith(_disposable);
  @@ -51,6 +46,7 @@ namespace TogglDesktop
  .Subscribe(_ => MainViewScroll.ScrollToVerticalOffset(ViewModel.CurrentTimeOffset - MainViewScroll.ActualHeight / 2))
  .DisposeWith(_disposable);
  ViewModel?.WhenAnyValue(x => x.FirstTimeEntryOffset)
  + .ObserveOn(RxApp.MainThreadScheduler)
  .Where(_ => !ViewModel.IsTodaySelected)
  .Subscribe(SetMainViewScrollOffset)
  .DisposeWith(_disposable);
  