Merge pull request #52 from shochdoerfer/feature/phpstan-phpunit

Add PHPStan PHPUnit extension

Author: shochdoerfer

composer.json

@@ -20,7 +20,9 @@
     "infection/infection": "^0.21.0",
     "madewithlove/license-checker": "^0.10.0",
     "phly/keep-a-changelog": "^2.11",
+    "phpstan/extension-installer": "^1.1",
     "phpstan/phpstan": "^0.12",
+    "phpstan/phpstan-phpunit": "^0.12.22",
     "phpstan/phpstan-strict-rules": "^0.12.9",
     "phpunit/phpunit": "^9.5",
     "roave/security-advisories": "dev-latest",