Update dependencies from DependenCI

Author: dependenci-bot

composer.json

@@ -1,7 +1,10 @@
 {
     "name": "laravel/laravel",
     "description": "The Laravel Framework.",
-    "keywords": ["framework", "laravel"],
+    "keywords": [
+        "framework",
+        "laravel"
+    ],
     "license": "MIT",
     "type": "project",
     "require": {
@@ -13,7 +16,7 @@
     "require-dev": {
         "fzaninotto/faker": "~1.4",
         "mockery/mockery": "0.9.*",
-        "phpunit/phpunit": "~5.7"
+        "phpunit/phpunit": "^6.3.0"
     },
     "repositories": [
         {
@@ -67,4 +70,4 @@
         "sort-packages": true,
         "optimize-autoloader": true
     }
-}
+}