add support for cmek in gcs module notification topic

modules/gcs/variables.tf

@@ -204,11 +204,13 @@ variable "name" {
 variable "notification_config" {
   description = "GCS Notification configuration."
   type = object({
-    enabled            = bool
-    payload_format     = string
-    topic_name         = string
-    sa_email           = string
-    create_topic       = optional(bool, true)
+    enabled        = bool
+    payload_format = string
+    sa_email       = string
+    topic_name     = string
+    create_topic = optional(object({
+      kms_key_id = optional(string)
+    }))
     event_types        = optional(list(string))
     custom_attributes  = optional(map(string))
     object_name_prefix = optional(string)