Update composer.json to add Laravel 6 support

Author: stefanbauer

composer.json

@@ -20,12 +20,12 @@
     ],
     "require": {
         "php": ">=5.6.0",
-        "illuminate/support": "5.2.*|5.3.*|5.4.*|5.5.*|5.6.*|5.7.*|5.8.*"
+        "illuminate/support": "5.2.*|5.3.*|5.4.*|5.5.*|5.6.*|5.7.*|5.8.*|^6.0"
     },
     "require-dev": {
         "mockery/mockery": "~0.9|~1.0|~1.1|~1.2",
         "phpunit/phpunit": "5.5.*|6.0.*|7.0.*|8.0.*",
-        "laravel/framework": "5.2.*|5.3.*|5.4.*|5.5.*|5.6.*|5.7.*|5.8.*"
+        "laravel/framework": "5.2.*|5.3.*|5.4.*|5.5.*|5.6.*|5.7.*|5.8.*|^6.0"
     },
     "autoload": {
         "psr-4": {