wrong return type in Swift_Attachment::fromPath method

[garak]

Q	A
Bug report?	yes
Feature request?	no
RFC?	no
How used?	Symfony
Swiftmailer version	6.1.3
PHP version	7.2.3

The phpdoc block in fromPath method is suggesting Swift_Mime_Attachment as a return type, while the method is returning an instance of self.
This is a problem when using a function with type-hinted parameter or return type.
Example:

<?php

function doSomethingWithAttachment(Swift_Attachment $attachment)
{
    // ....
}

$attachment = Swift_Attachment::fromPath('/foo.png');
doSomethingWithAttachment($attachment);

This is highlighted as error in IDE (e.g. phpStorm), because $attachment type is Swift_Mime_Attachment, while function is accepting Swift_Attachment.

Solution is trivial, I can provide a PR.