Remove obsolete message

src/Discord.Net.Providers.WS4Net/WS4NetProvider.cs

@@ -5,7 +5,6 @@ namespace Discord.Net.Providers.WS4Net
 {
     public static class WS4NetProvider
     {
-        [Obsolete("Please target .NET Core 2.1 or above")]
         public static readonly WebSocketProvider Instance = () => new WS4NetClient();
     }
 }