Bump redis-client from 0.20.0 to 0.21.0

Bumps [redis-client](https://github.com/redis-rb/redis-client) from 0.20.0 to 0.21.0.
- [Changelog](https://github.com/redis-rb/redis-client/blob/master/CHANGELOG.md)
- [Commits](redis-rb/redis-client@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: redis-client
  dependency-type: indirect
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Gemfile.lock

@@ -238,7 +238,7 @@ GEM
     rake (13.1.0)
     rdoc (6.6.2)
       psych (>= 4.0.0)
-    redis-client (0.20.0)
+    redis-client (0.21.0)
       connection_pool
     reline (0.4.3)
       io-console (~> 0.5)