Modify behaviour of .unsolved to prevent thread archiving in help forum

[rattus-rattus-rattus]

Currently, there is no way to prevent thread from being archived within the help forum once the .solved command has been invoked. After invocation, there is a 300 second delay before archiving, which was left to allow time for the .unsolved command to be used, if required. This was never implemented.

bot/plugins/clopen.py

Lines 729 to 738 in 9c91e60

	async def unsolved(conf: GuildConfig, post: Thread, reason: str) -> None:
	if not any(tag.id == conf.solved_tag_id for tag in post.applied_tags):
	return
	await set_solved_tags(conf, post, [conf.unsolved_tag_id], reason)
	await post.send(embed=unsolved_embed(reason), allowed_mentions=AllowedMentions.none())
	async def wait_close_post(post: Thread, reason: str) -> None:
	await asyncio.sleep(300) # TODO: what if the post is reopened in the meantime?
	await post.edit(archived=True, reason=reason)