Investigate using Valkey in place of Redis

[rfairburn]

There are likely performance benefits. For backwards compatibility, we need the modules to at least for not still also support the existing Redis modules.

[dima-naboka]

AWS also suggests using Valkey instead of the Redis engine to save money.

The underlying module cloudposse/elasticache-redis/aws started supporting Valkey in v1.7.0; however, apparently it was not working as expected until the very recent v.1.9.1 until they upgraded the AWS provider version to 5.73.0 (which you might need to do as well)