chore(deps): update redis requirement in /examples/using-resque

Updates the requirements on [redis](https://github.com/redis/redis-rb) to permit the latest version.
- [Changelog](https://github.com/redis/redis-rb/blob/master/CHANGELOG.md)
- [Commits](redis/redis-rb@v5.0.6...v5.0.8)

---
updated-dependencies:
- dependency-name: redis
  dependency-type: direct:production
...

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

examples/using-resque/Gemfile

@@ -2,4 +2,4 @@ source "https://rubygems.org"
 
 gem "resque", "2.5.0"
 
-gem "redis", "5.0.6"
+gem "redis", "5.0.8"