Update composer.json

Author: barryvdh

composer.json

@@ -11,7 +11,7 @@
     ],
     "require": {
         "php": ">=7",
-        "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/form": "^3.4|^4",
         "symfony/validator": "^3|^4",
         "symfony/twig-bridge": "^3|^4",