Fix build

Author: ondrejmirtes

composer.json

@@ -17,7 +17,7 @@
 		"ergebnis/composer-normalize": "^2.0.2",
 		"jakub-onderka/php-parallel-lint": "^1.0",
 		"phing/phing": "^2.16.0",
-		"phpstan/phpstan-phpunit": "^0.12",
+		"phpstan/phpstan-phpunit": "^0.12.3",
 		"phpstan/phpstan-strict-rules": "^0.12",
 		"phpunit/phpunit": "^7.5.18",
 		"slevomat/coding-standard": "^4.5.2"