fix: GuildMemberStore: unban returns user

fixes #2388

src/stores/GuildMemberStore.js

@@ -170,7 +170,7 @@ class GuildMemberStore extends DataStore {
     const id = this.client.users.resolveID(user);
     if (!id) throw new Error('BAN_RESOLVE_ID');
     return this.client.api.guilds(this.guild.id).bans[id].delete({ reason })
-      .then(() => user);
+      .then(() => this.client.users.resolve(user));
   }