Allow PHPUnit 9 (#1328)

Author: X-Coder264

composer.json

@@ -35,7 +35,7 @@
     "require-dev": {
         "mockery/mockery": "^1.0",
         "orchestra/testbench": "^4.4|^5.0",
-        "phpunit/phpunit": "^8.0"
+        "phpunit/phpunit": "^8.5|^9.3"
     },
     "autoload": {
         "psr-4": {