phpmd version 2.8 minimum.

composer.json

@@ -58,6 +58,7 @@
   "require-dev": {
     "irstea/dev-pack": "@stable",
     "irstea/phpstan-config": ">=1.0.2",
+    "phpmd/phpmd": ">=2.8",
     "roave/security-advisories": "dev-master"
   },
   "scripts": {