Update to phpunit 9

Author: AydinHassan

composer.json

@@ -14,7 +14,7 @@
         }
     ],
     "require-dev": {
-        "phpunit/phpunit": "^8.0",
+        "phpunit/phpunit": "^8.0 | ^9.0",
         "squizlabs/php_codesniffer": "^3.2",
         "phpstan/phpstan": "^0.12"
     },