add: orchestra/testbench 5.0 support

Author: Antonio Dal Sie

composer.json

@@ -40,7 +40,7 @@
         "ext-json": "*"
     },
     "require-dev": {
-        "orchestra/testbench": "3.5.*|3.6.*|3.7.*|3.8.*|3.9.*|4.0.*",
+        "orchestra/testbench": "3.5.*|3.6.*|3.7.*|3.8.*|3.9.*|4.0.*|5.0.*",
         "phpunit/phpunit": "^5.5|~6.0|~7.0|~8.0",
         "nunomaduro/larastan": "0.5.0",
         "mockery/mockery": "^1.2",