Bump phpspec/prophecy from 1.3.1 to 1.18.0

Bumps [phpspec/prophecy](https://github.com/phpspec/prophecy) from 1.3.1 to 1.18.0.
- [Release notes](https://github.com/phpspec/prophecy/releases)
- [Changelog](https://github.com/phpspec/prophecy/blob/master/CHANGES.md)
- [Commits](phpspec/prophecy@v1.3.1...v1.18.0)

---
updated-dependencies:
- dependency-name: phpspec/prophecy
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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