tools(deps-dev): Update icanhazstring/composer-unused requirement

Updates the requirements on [icanhazstring/composer-unused](https://github.com/composer-unused/composer-unused) to permit the latest version.
- [Release notes](https://github.com/composer-unused/composer-unused/releases)
- [Changelog](https://github.com/composer-unused/composer-unused/blob/main/CHANGELOG.md)
- [Commits](composer-unused/composer-unused@0.9.5...0.9.6)

---
updated-dependencies:
- dependency-name: icanhazstring/composer-unused
  dependency-version: 0.9.6
  dependency-type: direct:development
...

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

Author: dependabot[bot]

tools/composer-unused/composer.json

@@ -6,7 +6,7 @@
         "php": ">=8.4"
     },
     "require-dev": {
-        "icanhazstring/composer-unused": "0.9.5",
+        "icanhazstring/composer-unused": "0.9.6",
         "roave/security-advisories": "dev-latest"
     },
     "prefer-stable": true,