Bump react/promise-stream from 1.5.0 to 1.6.0

Bumps [react/promise-stream](https://github.com/reactphp/promise-stream) from 1.5.0 to 1.6.0.
- [Release notes](https://github.com/reactphp/promise-stream/releases)
- [Changelog](https://github.com/reactphp/promise-stream/blob/1.x/CHANGELOG.md)
- [Commits](reactphp/promise-stream@v1.5.0...v1.6.0)

---
updated-dependencies:
- dependency-name: react/promise-stream
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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