Bump phpmd/phpmd from 2.13.0 to 2.15.0

Bumps [phpmd/phpmd](https://github.com/phpmd/phpmd) from 2.13.0 to 2.15.0.
- [Release notes](https://github.com/phpmd/phpmd/releases)
- [Changelog](https://github.com/phpmd/phpmd/blob/master/CHANGELOG)
- [Commits](phpmd/phpmd@2.13.0...2.15.0)

---
updated-dependencies:
- dependency-name: phpmd/phpmd
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

composer.json

@@ -32,7 +32,7 @@
         "nelmio/api-doc-bundle": "^4.12",
         "ondrejmirtes/better-reflection": "4.3.*",
         "phpbench/phpbench": "^1.2",
-        "phpmd/phpmd": "2.13.*",
+        "phpmd/phpmd": "2.15.*",
         "phpstan/phpstan": "^1.10",
         "psr/cache": "^1.0 || ^2.0 || ^3.0",
         "psr/log": "^1.0 || ^2.0 || ^3.0",