feat: add support for guild forums

waiting https://github.com/discordjs/discord.js/pull/7791

src/util/Constants.js

@@ -654,6 +654,7 @@ exports.ActivityTypes = createEnum(['PLAYING', 'STREAMING', 'LISTENING', 'WATCHI
  * * `GUILD_PRIVATE_THREAD` - a guild text channel's private thread channel
  * * `GUILD_STAGE_VOICE` - a guild stage voice channel
  * * `GUILD_DIRECTORY` - the channel in a hub containing guilds
+ * * `GUILD_FORUM` - a guild channel that only contains threads
  * * `UNKNOWN` - a generic channel of unknown type, could be Channel or GuildChannel
  * @typedef {string} ChannelType
  * @see {@link https://discord.com/developers/docs/resources/channel#channel-object-channel-types}
@@ -673,6 +674,7 @@ exports.ChannelTypes = createEnum([
   'GUILD_PRIVATE_THREAD',
   'GUILD_STAGE_VOICE',
   'GUILD_DIRECTORY',
+  'GUILD_FORUM',
 ]);
 
 /**