remove unused directives

Jellyfin.Api/Controllers/NotificationsController.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.ComponentModel.DataAnnotations;
 using System.Linq;
 using System.Threading;
 using Jellyfin.Api.Constants;

Jellyfin.Api/Controllers/PlaystateController.cs

@@ -1,5 +1,4 @@
 using System;
-using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
 using System.Threading.Tasks;
 using Jellyfin.Api.Constants;