Bump php-coveralls/php-coveralls from 2.5.3 to 2.6.0 (#520)

Bumps [php-coveralls/php-coveralls](https://github.com/php-coveralls/php-coveralls) from 2.5.3 to 2.6.0.
- [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@v2.5.3...v2.6.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>