Drop php support for 8.1 and below.

Fix phpstan.

Merge pull request #35 from adriansuter/php-8.2

Add php 8.2.

Merge pull request #30 from adriansuter/patch-version

Fix docs.

Merge pull request #18 from adriansuter/patch-php

Drop PHP 7.1 and update PHPUnit

Merge pull request #17 from adriansuter/feature-phpstan

Add phpstan

Merge pull request #11 from adriansuter/version

Update version

Add coveralls badge

Delete parser test file