Upgrade production Redis to 6.2.3

[benlangfeld]

Staging, CI and local development are using 6.2.3. Production is using 6.0.9. This should be a safe and simple upgrade.

[benlangfeld]

Staging uses Heroku Redis while production uses Redis Enterprise Cloud. I couldn't find any way to specify the Redis version to be deployed there. The Heroku Redis addon allows minor version specification, but otherwise upgrades are managed by the platform. @compwron Do you have a preference for Redis Enterprise Cloud or Heroku Redis?