Update tomasvotruba/unused-public requirement from 0.3.8 to 0.3.9

Updates the requirements on [tomasvotruba/unused-public](https://github.com/TomasVotruba/unused-public) to permit the latest version.
- [Commits](TomasVotruba/unused-public@0.3.8...0.3.9)

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

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

composer.json

@@ -24,7 +24,7 @@
         "thecodingmachine/phpstan-safe-rule": "^1.2",
         "tomasvotruba/cognitive-complexity": "0.2.3",
         "tomasvotruba/type-coverage": "0.2.5",
-        "tomasvotruba/unused-public": "0.3.8"
+        "tomasvotruba/unused-public": "0.3.9"
     },
     "config": {
         "optimize-autoloader": true,