feat: add support for phpunit 13 (#60)

Author: W0rma

composer.json

@@ -11,7 +11,7 @@
     },
     "require": {
         "php": "^8.1",
-        "phpunit/phpunit": "^8.4 | ^9.0 | ^10.0 | ^11 | ^12"
+        "phpunit/phpunit": "^8.4 | ^9.0 | ^10.0 | ^11 | ^12 | ^13"
     },
     "require-dev": {
         "consolidation/robo": "^4.0"