Update composer dependencies to latest versions

- phpunit/phpunit: ^12.3 → ^13.1 (12.3.15 → 13.1.7)
- mockery/mockery: ^1.6 (1.6.12, already up to date)
- squizlabs/php_codesniffer: ^4.0 (4.0.1, already up to date)

All transitive dependencies updated accordingly.

Author: nicoSWD

composer.json

@@ -37,7 +37,7 @@
     "ext-ctype": "*"
   },
   "require-dev": {
-    "phpunit/phpunit": "^12.3",
+    "phpunit/phpunit": "^13.1",
     "mockery/mockery": "^1.6",
     "squizlabs/php_codesniffer": "^4.0"
   },