composer(deps-dev): update tomasvotruba/unused-public requirement

Updates the requirements on [tomasvotruba/unused-public](https://github.com/TomasVotruba/unused-public) to permit the latest version.

Updates `tomasvotruba/unused-public` to 0.3.9
- [Commits](TomasVotruba/unused-public@0.3.8...0.3.9)

---
updated-dependencies:
- dependency-name: tomasvotruba/unused-public
  dependency-type: direct:development
  dependency-group: minor-patch-dependencies
...

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

composer.json

@@ -45,7 +45,7 @@
     "symplify/phpstan-rules": "^12.4.9",
     "tomasvotruba/cognitive-complexity": "^0.2.3",
     "tomasvotruba/type-coverage": "^0.2.8",
-    "tomasvotruba/unused-public": "^0.3.8"
+    "tomasvotruba/unused-public": "^0.3.9"
   },
   "minimum-stability": "stable",
   "prefer-stable": true,