Make member and user `ref object of DiscordObject`

src/member.nim

@@ -1,6 +1,6 @@
 import discordobject, user, json
 
-type GuildMember* = object of DiscordObject
+type GuildMember* = ref object of DiscordObject
     ## This type is a guild member.
     user*: User ## The user this guild member represents.
     nick*: string ## This users guild nickname.

src/user.nim

@@ -6,7 +6,7 @@ type
         nitroClassic = 1,
         nitro = 2
 
-    User* = object of DiscordObject
+    User* = ref object of DiscordObject
         ## This type is a discord user.
         username*: string ## The user's username, not unique across the platform.
         discriminator*: cushort ## The user's 4-digit discord-tag.