Updated PHPUnit dependency version

Author: logical-and

composer.json

@@ -38,7 +38,7 @@
     "require-dev": {
         "symfony/http-foundation": "~2.1",
         "predis/predis": "0.8.*@dev",
-        "phpunit/phpunit": "~4.4"
+        "phpunit/phpunit": "~4.6"
     },
     "suggest": {
         "symfony/http-foundation": "Allows using the Symfony Session storage backend.",