Bump dev-master to 5.0-dev

Author: yajra

composer.json

@@ -36,7 +36,7 @@
   },
   "extra": {
     "branch-alias": {
-      "dev-master": "4.0-dev"
+      "dev-master": "5.0-dev"
     },
     "laravel": {
       "providers": [