fix(subscriptions): reply notifications not working

[SychO9]

Fixes #3443

Changes proposed in this pull request:
As mentioned in the issue the reply notification job now receives an updated $lastPostNumber and because new post numbers are now guaranteed to be the max+1 (last post number before it + 1) then we can assume the job can use $lastPostNumber - 1.

Necessity

• Has the problem that is being solved here been clearly explained?
• If applicable, have various options for solving this problem been considered?
• For core PRs, does this need to be in core, or could it be in an extension?
• Are we willing to maintain this for years / potentially forever?

Confirmed

• Frontend changes: tested on a local Flarum installation.
• Backend changes: tests are green (run composer test).
• Core developer confirmed locally this works as intended.
• Tests have been added, or are not appropriate here.

[davwheat]

Could we run into issues if two people post simultaneously and the queue processes the jobs late? I'd assume that the last post number would then refer to a later post than what we want, wouldn't it?

[SychO9]

If I understand you correctly, the post number would still point to the correct value since it is provided to the job object at posting time. So no matter when the job processes it'll have the correct number because it isn't looking it up but using what it was given:

framework/extensions/subscriptions/src/Job/SendReplyNotification.php

Lines 38 to 42 in 0a3f449

	public function __construct(Post $post, $lastPostNumber)
	{
	$this->post = $post;
	$this->lastPostNumber = $lastPostNumber;
	}

[davwheat]

Oh yes, sorry, I was being a total idiot.

[SychO9]

Never!