Establish compatibility with Laravel 6

Author: mzur

.gitignore

@@ -1 +1,2 @@
 /vendor/
+.phpunit.result.cache

composer.json

@@ -11,10 +11,10 @@
     ],
     "require": {
         "guzzlehttp/guzzle": "~6.0",
-        "illuminate/queue": "^5.7 >=5.7.7",
-        "illuminate/support": "^5.7 >=5.7.7",
-        "illuminate/contracts": "^5.7 >=5.7.7",
-        "illuminate/routing": "^5.7 >=5.7.7"
+        "illuminate/queue": "^5.7 >=5.7.7 | ^6.0",
+        "illuminate/support": "^5.7 >=5.7.7 | ^6.0",
+        "illuminate/contracts": "^5.7 >=5.7.7 | ^6.0",
+        "illuminate/routing": "^5.7 >=5.7.7 | ^6.0"
     },
     "autoload": {
         "psr-4": {
@@ -37,8 +37,8 @@
         }
     },
     "require-dev": {
-        "phpunit/phpunit": "^7.4",
+        "phpunit/phpunit": "^8.0",
         "mockery/mockery": "^1.2",
-        "laravel/laravel": "^5.7 >=5.7.7"
+        "laravel/laravel": "^5.7 >=5.7.7 | ^6.0"
     }
 }