Fix: dynamic properties deprecation

[richardbrinkman]

Since PHP 8.2 dynamic properties are deprecated. See https://www.php.net/manual/en/migration82.deprecated.php The send_or_fail function sets a greeting variable (which is not used anywhere) that is not a property of the Mail_smtp class.

[schengawegga]

Merged. Thanks for your PR. I only changed the line length in the comment of the var declaration and the tabs into spaces on the indents. Thank you for your contribution.

[richardbrinkman]

@schengawegga , is there a release planned yet containing this merge request?

[schengawegga]

@richardbrinkman yes, I will plan a release, but I am very busy at the moment. And I want to test the PR well before I release an new version. So give me a little bit more time to test your PR. Thank you. I appreciate your effort in this project.

[francescozanoni]

Hi.
Please be aware that other properties are dynamically created, such as $queued_as:
Creation of dynamic property Mail_smtp::$queued_as is deprecated
Thanks.

[schengawegga]

Hi. Please be aware that other properties are dynamically created, such as $queued_as: Creation of dynamic property Mail_smtp::$queued_as is deprecated Thanks.

Thanks for your hint.