More warning fixes

MediaBrowser.Controller/Providers/AlbumInfo.cs

@@ -9,7 +9,7 @@ namespace MediaBrowser.Controller.Providers
         /// Gets or sets the album artist.
         /// </summary>
         /// <value>The album artist.</value>
-        public string[] AlbumArtists { get; set; }
+        public IReadOnlyList<string> AlbumArtists { get; set; }
 
         /// <summary>
         /// Gets or sets the artist provider ids.

MediaBrowser.Controller/Providers/MusicVideoInfo.cs

@@ -1,7 +1,9 @@
+using System.Collections.Generic;
+
 namespace MediaBrowser.Controller.Providers
 {
     public class MusicVideoInfo : ItemLookupInfo
     {
-        public string[] Artists { get; set; }
+        public IReadOnlyList<string> Artists { get; set; }
     }
 }

MediaBrowser.Controller/Providers/SongInfo.cs

@@ -1,12 +1,15 @@
 using System;
+using System.Collections.Generic;
 
 namespace MediaBrowser.Controller.Providers
 {
     public class SongInfo : ItemLookupInfo
     {
-        public string[] AlbumArtists { get; set; }
+        public IReadOnlyList<string> AlbumArtists { get; set; }
+
         public string Album { get; set; }
-        public string[] Artists { get; set; }
+
+        public IReadOnlyList<string> Artists { get; set; }
 
         public SongInfo()
         {