Update composer.json

Author: z-song

composer.json

@@ -14,11 +14,10 @@
     "require": {
         "php": ">=7.0.0",
         "laravel/framework": "~5.5",
-        "encore/laravel-admin": "1.5.*"
+        "encore/laravel-admin": "~1.5"
     },
     "require-dev": {
-        "phpunit/phpunit": "~6.0",
-        "laravel/laravel": "~5.5"
+        "phpunit/phpunit": "~6.0"
     },
     "autoload": {
         "psr-4": {