Always install nikic/php-parser v5

Author: ondrejmirtes

composer.json

@@ -13,6 +13,7 @@
 		"phpunit/phpunit": "<7.0"
 	},
 	"require-dev": {
+		"nikic/php-parser": "^5",
 		"php-parallel-lint/php-parallel-lint": "^1.2",
 		"phpstan/phpstan-deprecation-rules": "^2.0",
 		"phpstan/phpstan-strict-rules": "^2.0",