minor fix

Author: Nyholm

composer.json

@@ -23,8 +23,8 @@
         "paragonie/random_compat": "^2.0"
     },
     "require-dev": {
-        "guzzlehttp/guzzle": "~5.0",
-        "mockery/mockery": "^0.8",
+        "phpunit/phpunit": "^5.7.5",
+        "mockery/mockery": "^0.9",
         "php-http/guzzle6-adapter": "^1.0",
         "php-http/message": "^1.0",
         "guzzlehttp/psr7": "^1.0"