Allow PHP 8

[FlorianVen]

Hi there,

We're looking to use this package in a PHP 8 codebase. This PR bumps the composer PHP requirement to ^8.0 so it can be installed without problems.

Our testing shows no issues running the code under PHP 8. The only issue was phpunit/phpunit requiring php: ^7.1. Since phpunit is not used in the package I have removed the dependency entirely. If this dependency is somehow required please let me know what version would be acceptable. Additionally, PHPCompatibility shows no issues:

$ composer global require phpcompatibility/php-compatibility
$ ./bin/phpcs -p ./src --standard=~/.config/composer/vendor/phpcompatibility/php-compatibility/PHPCompatibility --runtime-set testVersion 8.0

............................................................ 60 / 88 (68%)
............................                                 88 / 88 (100%)


Time: 937ms; Memory: 12MB

[FlorianVen]

@dpdplugin any way to move this forward?

[dpdplugin]

Hi @FlorianVen ,

Thank you for your contribution