composer(deps-dev): bump ergebnis/php-cs-fixer-config

Bumps [ergebnis/php-cs-fixer-config](/~https://github.com/ergebnis/php-cs-fixer-config) from 6.39.0 to 6.40.0.
- [Release notes](/~https://github.com/ergebnis/php-cs-fixer-config/releases)
- [Changelog](/~https://github.com/ergebnis/php-cs-fixer-config/blob/main/CHANGELOG.md)
- [Commits](ergebnis/php-cs-fixer-config@6.39.0...6.40.0)

---
updated-dependencies:
- dependency-name: ergebnis/php-cs-fixer-config
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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