test: phpcs, phpmd for #54

Author: g105b

composer.json

@@ -9,8 +9,10 @@
 	},
 
 	"require-dev": {
-		"phpstan/phpstan": "^v1.8",
-		"phpunit/phpunit": "^10.1"
+		"phpstan/phpstan": "^1.10",
+		"phpunit/phpunit": "^10.1",
+		"phpmd/phpmd": "^2.13",
+		"squizlabs/php_codesniffer": "^3.7"
 	},
 
 	"license": "MIT",