Made player_name nullable

Author: Mikkel Sørensen

Runtime/Game/Requests/LootLockerSessionRequest.cs

@@ -49,7 +49,7 @@ public class LootLockerSessionResponse : LootLockerResponse
         /// <summary>
         /// The player's name if it has been set by using SetPlayerName().
         /// </summary>
-        public string player_name { get; set; }
+        public string? player_name { get; set; }
         /// <summary>
         /// The session token that can now be used to use further LootLocker functionality. We store and use this for you.
         /// </summary>