Update deps

Author: jlinskeseder

composer.json

@@ -22,7 +22,7 @@
         "karriere/phpspec-matchers": "^1.0",
         "phpmd/phpmd": "^2.4",
         "phpspec/phpspec": "^3.2",
-        "squizlabs/php_codesniffer": "^3.0.0RC2",
+        "squizlabs/php_codesniffer": "^2.8.0",
         "symfony/process": "^3.2",
         "symfony/console": "^3.2"
     },