Add Laravel 8 support

Author: pionl

composer.json

@@ -15,17 +15,17 @@
     "test": "./vendor/bin/phpunit"
   },
   "require": {
-    "illuminate/http": "5.2 - 5.8 | ^6.0 | ^7.0",
-    "illuminate/console": "5.2 - 5.8 | ^6.0 | ^7.0",
-    "illuminate/support": "5.2 - 5.8 | ^6.0 | ^7.0",
-    "illuminate/filesystem": "5.2 - 5.8 | ^6.0 | ^7.0"
+    "illuminate/http": "5.2 - 5.8 | ^6.0 | ^7.0 | ^8.0",
+    "illuminate/console": "5.2 - 5.8 | ^6.0 | ^7.0 | ^8.0",
+    "illuminate/support": "5.2 - 5.8 | ^6.0 | ^7.0 | ^8.0",
+    "illuminate/filesystem": "5.2 - 5.8 | ^6.0 | ^7.0 | ^8.0"
   },
   "require-dev": {
-    "laravel/laravel": "5.2 - 5.8 | ^6.0 | ^7.0",
-    "phpunit/phpunit": "5.7 | 6.0 | 7.0 | 7.5 | 8.4 | ^8.5",
+    "laravel/laravel": "5.2 - 5.8 | ^6.0 | ^7.0 | ^8.0",
+    "phpunit/phpunit": "5.7 | 6.0 | 7.0 | 7.5 | 8.4 | ^8.5 | ^9.3",
     "mockery/mockery": "^1.1.0 | ^1.3.0",
     "friendsofphp/php-cs-fixer": "^2.16.0",
-    "overtrue/phplint": "^1.1"
+    "overtrue/phplint": "^1.1 | ^2.0"
   },
   "autoload": {
     "psr-4": {