Jatin Goyal

Switch Redis to Valkey in deploy template and tests

2

As mentioned by @dhh in https://github.com/basecamp/kamal/pull/1044#issuecomment-2394796495, this PR replaces Redis with [Valkey](https://github.com/valkey-io/valkey?tab=License-1-ov-file) (the FOSS fork of Redis) in deploy template and tests. The deploy template now uses [`valkey/valkey:8`](https://hub.docker.com/r/valkey/valkey/tags) image for...

This PR updates Redis occurrences with Valkey in v2 docs in line with changes via https://github.com/basecamp/kamal/pull/1079