Undo Remove phpmetrics/phpmetrics until it allows for "nikic/php-parser: ^5"

composer.json

@@ -59,6 +59,7 @@
     "mikey179/vfsstream": "*",
     "php-parallel-lint/php-parallel-lint": "*",
     "phpmd/phpmd": "*",
+    "phpmetrics/phpmetrics": "^2.8",
     "phpspec/prophecy": "*",
     "phpspec/prophecy-phpunit": "*",
     "phpstan/extension-installer": "*",