Enhancement: Require a more recent version of phpunit/phpunit

Author: localheinz

composer.json

@@ -40,7 +40,7 @@
     },
     "require-dev": {
         "json-schema/JSON-Schema-Test-Suite": "1.1.0",
-        "phpunit/phpunit": "~3.7",
+        "phpunit/phpunit": "^4.8.22",
         "phpdocumentor/phpdocumentor": "~2"
     },
     "autoload": {