Update composer to support php8

[marcingy]

No description provided.

[marcingy]

Local test

~/checkouts/systemctl-php$ php -v
PHP 8.0.6 (cli) (built: May 13 2021 05:34:34) ( NTS )
Copyright (c) The PHP Group
Zend Engine v4.0.6, Copyright (c) Zend Technologies
with Zend OPcache v8.0.6, Copyright (c), by Zend Technologies
~/checkouts/systemctl-php$ composer test

vendor/bin/phpunit
PHPUnit 9.5.4 by Sebastian Bergmann and contributors.

............................................................... 63 / 128 ( 49%)
............................................................... 126 / 128 ( 98%)
.. 128 / 128 (100%)

Time: 00:00.070, Memory: 10.00 MB

OK (128 tests, 192 assertions)

[icanhazstring]

Merged. Thank you 👍

[icanhazstring]

Tagged with 0.8.2
https://github.com/icanhazstring/systemctl-php/releases/tag/0.8.2

[marcingy]

Thanks :)