Bump redis-namespace from 1.7.0 to 1.9.0

Bumps [redis-namespace](https://github.com/resque/redis-namespace) from 1.7.0 to 1.9.0.
- [Release notes](https://github.com/resque/redis-namespace/releases)
- [Changelog](https://github.com/resque/redis-namespace/blob/master/CHANGELOG.md)
- [Commits](https://github.com/resque/redis-namespace/compare/v1.7.0...v1.9

)

---
updated-dependencies:
- dependency-name: redis-namespace
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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