Update composer.json

Author: barryvdh

composer.json

@@ -11,7 +11,7 @@
     ],
     "require": {
         "php": ">=5.5",
-        "illuminate/support": "5.5.x|5.6.x|5.7.x",
+        "illuminate/support": "5.5.x|5.6.x|5.7.x|5.8.x",
         "symfony/console": "^3.2|^4",
         "symfony/http-kernel": "^3.2|^4",
         "barryvdh/laravel-stack-middleware": "^1.0"