Updated orchestra testbench to support Laravel 8

Author: unicodeveloper

composer.json

@@ -21,7 +21,7 @@
     "require-dev": {
         "phpunit/phpunit": "^8.0",
         "mockery/mockery": "^1.1",
-        "orchestra/testbench": "~3|~4",
+        "orchestra/testbench": "~4|~5|~6",
         "sempro/phpunit-pretty-print": "^1.0"
     },
     "autoload": {