Ensure PHP 8.3 compatibility

Pin symfony/yaml to ^7.4 — v8.x requires PHP >=8.4.1 which is
incompatible with our PHP 8.3 requirement. All packages that depend
on symfony/yaml accept ^7.0, so this is a safe downgrade.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

composer.json

@@ -12,8 +12,9 @@
         "laravel/framework": "^13.8",
         "laravel/scout": "^11.2",
         "laravel/tinker": "^3.0",
-        "spatie/laravel-sitemap": "^8.1",
-        "spatie/laravel-sluggable": "^4.0"
+        "spatie/laravel-sitemap": "^7.4",
+        "spatie/laravel-sluggable": "^4.0",
+        "symfony/yaml": "^7.4"
     },
     "require-dev": {
         "fakerphp/faker": "^1.23",