Add marshal by ref to entities

src/Discord.Net.Rest/Entities/RestEntity.cs

@@ -1,8 +1,8 @@
-using System;
+using System;
 
 namespace Discord.Rest
 {
-    public abstract class RestEntity<T> : IEntity<T>
+    public abstract class RestEntity<T> : MarshalByRefObject, IEntity<T>
         where T : IEquatable<T>
     {
         internal BaseDiscordClient Discord { get; }

src/Discord.Net.WebSocket/Entities/SocketEntity.cs

@@ -2,7 +2,7 @@ using System;
 
 namespace Discord.WebSocket
 {
-    public abstract class SocketEntity<T> : IEntity<T>
+    public abstract class SocketEntity<T> : MarshalByRefObject, IEntity<T>
         where T : IEquatable<T>
     {
         internal DiscordSocketClient Discord { get; }