[PHP 8.4] Fixes for implicit nullability deprecation

[Ayesh]

Fixes all issues that emit deprecation notices on PHP 8.4 for implicit nullable parameter type declarations.

See:

• RFC
• PHP 8.4: Implicitly nullable parameter declarations deprecated

[ThomasLandauer]

PHP 8.4 was released meanwhile, so please merge this and release a new version.

[ghnp5]

Thank you for making the change.
But looks like this project/package is dead...
Maybe you could create a new composer package, that contains this fix?
Thanks!

[ThomasLandauer]

I switched to https://github.com/Webklex/php-imap meanwhile.

[mirko-pagliai]

All of this is truly a great shame.

[mirko-pagliai]

In the end I migrated to another package like others.

We all know that for these projects we only make available our free time, when we can and if we can.
But this PR has existed for more than a year, it was enough to merge and publish a new release. Two minutes were enough. Or ask if someone wants to take over the management of the project, since it has been stopped for a few years. Or even mark it as abandoned and announce that you no longer want to carry it forward.

It's a real shame.