Merge branch 'sh-update-redis-4.1.3' into 'master'

Update redis-rb to 4.1.3 to match GitLab CE/EE

See merge request gitlab-org/gitlab-exporter!106
2 jobs for master in 47 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed rspec #6345980

00:00:45

passed rubocop #6345981

00:00:47