Re-allow PHPSpec 3

Author: Jean85

composer.json

@@ -18,7 +18,7 @@
         "symfony/options-resolver": "^2.6 || ^3.0 || ^4.0"
     },
     "require-dev": {
-        "phpspec/phpspec": "^4.2",
+        "phpspec/phpspec": "^3.4 || ^4.2",
         "guzzlehttp/psr7": "^1.4"
     },
     "suggest": {