Make letter amendments queue FIFO

Author: stevebux

infrastructure/terraform/components/api/module_sqs_letter_updates.tf

@@ -2,11 +2,14 @@ module "sqs_letter_updates" {
   source = "https://github.com/NHSDigital/nhs-notify-shared-modules/releases/download/v2.0.26/terraform-sqs.zip"
 
   aws_account_id = var.aws_account_id
-  component      = var.component
-  environment    = var.environment
-  project        = var.project
-  region         = var.region
-  name           = "letter-updates"
+  component                   = var.component
+  environment                 = var.environment
+  project                     = var.project
+  region                      = var.region
+  name                        = "letter-updates"
+  fifo_queue                  = true
+  content_based_deduplication = true
+
 
   sqs_kms_key_arn = module.kms.key_arn