Merge pull request #13453 from luzpaz/extentions-typo

Fix source typo

MediaBrowser.Controller/Entities/Audio/IHasAlbumArtist.cs

@@ -22,7 +22,7 @@ namespace MediaBrowser.Controller.Entities.Audio
         IReadOnlyList<string> Artists { get; set; }
     }
 
-    public static class Extentions
+    public static class Extensions
     {
         public static IEnumerable<string> GetAllArtists<T>(this T item)
             where T : IHasArtist, IHasAlbumArtist