Remove unused using

Jellyfin.Api/Controllers/VideoAttachmentsController.cs

@@ -7,7 +7,6 @@ using System.Threading.Tasks;
 using MediaBrowser.Common.Extensions;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.MediaEncoding;
-using MediaBrowser.Model.Net;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;