Fix build

Jellyfin.Api/Controllers/LibraryStructureController.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.Globalization;
 using System.IO;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Jellyfin.Api.Extensions;