ci: test against PHP 8.5

Author: W0rma

.github/workflows/phpunit.yml

@@ -16,7 +16,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php-versions: ['8.1', '8.2', '8.3', '8.4']
+        php-versions: ['8.1', '8.2', '8.3', '8.4', '8.5']
 
     name: PHP ${{ matrix.php-versions }}