Update php-soap/encoding requirement from ^0.16.0 to ^0.16.0 || ^0.18.0

Updates the requirements on [php-soap/encoding](https://github.com/php-soap/encoding) to permit the latest version.
- [Release notes](https://github.com/php-soap/encoding/releases)
- [Commits](php-soap/encoding@0.16.0...0.18.0)

---
updated-dependencies:
- dependency-name: php-soap/encoding
  dependency-type: direct:development
...

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

composer.json

@@ -30,7 +30,7 @@
     },
     "require-dev": {
         "nyholm/psr7": "^1.8",
-        "php-soap/encoding": "^0.16.0",
+        "php-soap/encoding": "^0.16.0 || ^0.18.0",
         "vimeo/psalm": "^5.26",
         "php-standard-library/psalm-plugin": "^2.3",
         "phpunit/phpunit": "^10.5.40",