Upgrade Pest to ^3.0 for PHP 8.5 compatibility

Pest ^2.0 pins PHPUnit 10.x, which has no paratest release compatible
with PHP 8.5. Composer can no longer resolve the dev dependencies on
PHP 8.5. Pest ^3.0 resolves cleanly (PHPUnit 11.x) and the existing
test suite passes unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: ziimk

composer.json

@@ -23,7 +23,7 @@
         "guzzlehttp/psr7": "^2.0"
     },
     "require-dev": {
-        "pestphp/pest": "^2.0",
+        "pestphp/pest": "^3.0",
         "phpstan/phpstan": "^1.10"
     },
     "autoload": {