Bump php-coveralls/php-coveralls in the dependencies group (#523)

Bumps the dependencies group with 1 update: [php-coveralls/php-coveralls](https://github.com/php-coveralls/php-coveralls).


Updates `php-coveralls/php-coveralls` from 2.9.0 to 2.9.1
- [Release notes](https://github.com/php-coveralls/php-coveralls/releases)
- [Changelog](https://github.com/php-coveralls/php-coveralls/blob/master/CHANGELOG.md)
- [Commits](php-coveralls/php-coveralls@v2.9.0...v2.9.1)

---
updated-dependencies:
- dependency-name: php-coveralls/php-coveralls
  dependency-version: 2.9.1
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: dependencies
...

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Author: dependabot[bot]