feat: add InvitableMixin to GuildForum (#1611)

You can invite people to a forum, after all.

Author: AstreaTSS

interactions/models/discord/channel.py

@@ -2389,7 +2389,7 @@ async def close_stage(self, reason: Absent[Optional[str]] = MISSING) -> None:
 
 
 @attrs.define(eq=False, order=False, hash=False, kw_only=True)
-class GuildForum(GuildChannel):
+class GuildForum(GuildChannel, InvitableMixin):
     available_tags: List[ThreadTag] = attrs.field(repr=False, factory=list)
     """A list of tags available to assign to threads"""
     default_reaction_emoji: Optional[DefaultReaction] = attrs.field(repr=False, default=None)