Update phpunit package in composer.json file.

Author: candasm

composer.json

@@ -14,7 +14,7 @@
   },
   "require-dev": {
     "squizlabs/php_codesniffer": "^2.8",
-    "phpunit/phpunit": "^5.7"
+    "phpunit/phpunit": "^4.8"
   },
   "autoload": {
     "psr-0": {