message: Add border shadow for the notification (win)
diff: <Setter Property="Template">
  <Setter.Value>
  <ControlTemplate TargetType="{x:Type togglDesktop:TogglNotification}">
  - <Border Background="{DynamicResource Toggl.Background}">
  + <Border Background="{DynamicResource Toggl.Background}" Margin="16 16 8 8">
  <Border.Effect>
  <DropShadowEffect
  Direction="270"
  - ShadowDepth="2"
  - BlurRadius="7"
  - Opacity="0.35" />
  + ShadowDepth="5"
  + BlurRadius="14"
  + Opacity="0.28" />
  </Border.Effect>
  <StackPanel>
  