feat: Configure notify-keyspace-events for redis

[levinandrew]

Enable subscription for key updates

Terraform plan

Terraform will perform the following actions:
...
  # module.wandb.module.redis[0].google_redis_instance.default will be updated in-place
  ~ resource "google_redis_instance" "default" {
        id                       = "projects/playground-111/locations/us-central1/instances/andrew-levin-gcp-two-redis"
        name                     = "andrew-levin-gcp-two-redis"
      ~ redis_configs            = {
          + "notify-keyspace-events" = "K$"
        }
...
Plan: 0 to add, 1 to change, 0 to destroy.

Subscribing test

After applying the changes, I connected to the redis instance from two terminal windows. In one window I did

10.30.0.4:6378> PSUBSCRIBE __keyspace@0__:*
Reading messages... (press Ctrl-C to quit)
1) "psubscribe"
2) "__keyspace@0__:*"
3) (integer) 1

then in another I did

10.30.0.4:6378> SET testKey testValue
OK

then in the first window I saw the update come through

1) "pmessage"
2) "__keyspace@0__:*"
3) "__keyspace@0__:testKey"
4) "set"

[jsbroks]

This PR is included in version 6.2.0 🎉