Composer: update version constraints
Composer: update version constraints

Follow up on c1a63391084a9cb55bba53cb341049428aa3a1c0 which enabled PHP 8.1 support, let's make sure that the version constraints of (dev) dependencies are such that PHP 8.1 compatible versions will be installed.

Refs:
* https://github.com/php-parallel-lint/PHP-Parallel-Lint/releases
* https://github.com/squizlabs/PHP_CodeSniffer/releases

jimjag/PHPMailer,PHPMailer/PHPMailer,nawawi/PHPMailer,jimjag/PHPMailer,nawawi/PHPMailer,PHPMailer/PHPMailer