Update mail.stub to use new Mailable syntax

[dannyrevenant]

Synopsis:

In this PR, Taylor updated the default syntax for Mailables. This is now the default in laravel core and in the docs.

Proposed Syntax:

As per the docs/repo, but presumably without the __construct as I think we usually skip that?

Expected Behavior:

mail.stub is generated with the new syntax

I think this should "just work"

[jasonmccreary]

While Blueprint does aim to be the latest, greatest with Laravel features, this might be too fast.

I'm glad to do this after the Laravel X release. But for now, we'll keep the Mailables as they were at the time of Laravel 9's release.

If you want this, you can update your own Mailable stub or submit a PR with a configuration option to use the "new" syntax.