composer(deps-dev): bump ergebnis/phpunit-slow-test-detector

Bumps [ergebnis/phpunit-slow-test-detector](https://github.com/ergebnis/phpunit-slow-test-detector) from 2.14.0 to 2.15.0.
- [Release notes](https://github.com/ergebnis/phpunit-slow-test-detector/releases)
- [Changelog](https://github.com/ergebnis/phpunit-slow-test-detector/blob/main/CHANGELOG.md)
- [Commits](ergebnis/phpunit-slow-test-detector@2.14.0...2.15.0)

---
updated-dependencies:
- dependency-name: ergebnis/phpunit-slow-test-detector
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

composer.json

@@ -31,7 +31,7 @@
     "ergebnis/composer-normalize": "^2.42.0",
     "ergebnis/license": "^2.4.0",
     "ergebnis/php-cs-fixer-config": "~6.30.1",
-    "ergebnis/phpunit-slow-test-detector": "^2.14.0",
+    "ergebnis/phpunit-slow-test-detector": "^2.15.0",
     "fakerphp/faker": "^1.23.1",
     "infection/infection": "~0.27.11",
     "phpunit/phpunit": "^10.5.20",