Make kms key input type consistent as string

Author: OlamideOl1

Diff for: elasticache-redis/replication-group/main.tf

@@ -242,5 +242,5 @@ locals {
     local.shared_security_group_ids
   )
 
-  primary_kms_key = var.enable_kms ? (var.kms_key == null ? module.customer_kms.kms_key_arn : var.kms_key.id) : var.kms_key
+  primary_kms_key = var.enable_kms ? (var.kms_key_id == null ? module.customer_kms.kms_key_arn : var.kms_key_id) : var.kms_key_id
 }

Diff for: elasticache-redis/replication-group/variables.tf

@@ -10,9 +10,9 @@ variable "at_rest_encryption_enabled" {
   default     = true
 }
 
-variable "kms_key" {
-  description = "Custom KMS key to encrypt data at rest"
-  type        = object({ arn = string })
+variable "kms_key_id" {
+  description = "KMS key to encrypt data at rest"
+  type        = string
   default     = null
 }