composer(deps-dev): bump ergebnis/composer-normalize

Bumps [ergebnis/composer-normalize](https://github.com/ergebnis/composer-normalize) from 2.18.0 to 2.21.0.
- [Release notes](https://github.com/ergebnis/composer-normalize/releases)
- [Changelog](https://github.com/ergebnis/composer-normalize/blob/main/CHANGELOG.md)
- [Commits](ergebnis/composer-normalize@2.18.0...2.21.0)

---
updated-dependencies:
- dependency-name: ergebnis/composer-normalize
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

composer.json

@@ -25,7 +25,7 @@
     "justinrainbow/json-schema": "^5.2.10"
   },
   "require-dev": {
-    "ergebnis/composer-normalize": "^2.18.0",
+    "ergebnis/composer-normalize": "^2.21.0",
     "ergebnis/data-provider": "^1.0.0",
     "ergebnis/license": "^1.1.0",
     "ergebnis/php-cs-fixer-config": "~3.4.0",