Merge pull request #12 from Hyunk3l/codex/pr-04-phpunit13

Upgrade PHPUnit to v13 and migrate config schema

Author: Hyunk3l

.github/workflows/php.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-version: [ '8.3', '8.4' ]
+        php-version: [ '8.4' ]
 
     steps:
     - uses: actions/checkout@v4

composer.json

@@ -22,7 +22,7 @@
         }
     },
     "require-dev": {
-        "phpunit/phpunit": "^11",
+        "phpunit/phpunit": "^13.0",
         "squizlabs/php_codesniffer": "^4.0"
     },
     "scripts": {