Update saloonphp/saloon requirement from ^3.0 to ^4.0

Updates the requirements on [saloonphp/saloon](https://github.com/saloonphp/saloon) to permit the latest version.
- [Release notes](https://github.com/saloonphp/saloon/releases)
- [Commits](saloonphp/saloon@v3.0.0...v4.0.0)

---
updated-dependencies:
- dependency-name: saloonphp/saloon
  dependency-version: 4.0.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

composer.json

@@ -18,7 +18,7 @@
     "require": {
         "php": "^8.4",
         "illuminate/contracts": "^11.0||^12.0",
-        "saloonphp/saloon": "^3.0",
+        "saloonphp/saloon": "^4.0",
         "spatie/laravel-data": "^4.20",
         "spatie/laravel-package-tools": "^1.16"
     },