Update Laravel version restriction to ^6.0

Author: pionl

composer.json

@@ -15,13 +15,13 @@
     "test": "./vendor/bin/phpunit"
   },
   "require": {
-    "illuminate/http": "5.1 - 6.5",
-    "illuminate/console": "5.1 - 6.5",
-    "illuminate/support": "5.1 - 6.5",
-    "illuminate/filesystem": "5.1 - 6.5"
+    "illuminate/http": "5.1 - 5.8|^6.0",
+    "illuminate/console": "5.1 - 5.8|^6.0",
+    "illuminate/support": "5.1 - 5.8|^6.0",
+    "illuminate/filesystem": "5.1 - 5.8|^6.0"
   },
   "require-dev": {
-    "laravel/laravel": "5.1 - 6.4",
+    "laravel/laravel": "5.1 - 5.8|^6.0",
     "phpunit/phpunit": "5.7 || 6.0 || 7.0 || 7.5 || 8.4",
     "mockery/mockery": "^1.1.0",
     "friendsofphp/php-cs-fixer": "^2.16.0",