Cleaned up paged enumerables

src/Discord.Net.Rest/Entities/Channels/RestChannel.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Collections.Immutable;
 using System.Diagnostics;
 using System.Linq;
 using System.Threading.Tasks;
@@ -50,6 +49,6 @@ namespace Discord.Rest
         Task<IUser> IChannel.GetUserAsync(ulong id, CacheMode mode)
             => Task.FromResult<IUser>(null); //Overriden
         IAsyncEnumerable<IReadOnlyCollection<IUser>> IChannel.GetUsersAsync(CacheMode mode)
-            => ImmutableArray.Create<IReadOnlyCollection<IUser>>().ToAsyncEnumerable(); //Overriden
+            => AsyncEnumerable.Empty<IReadOnlyCollection<IUser>>(); //Overriden
     }
 }