chore(deps): update terraform terraform-ibm-modules/icd-postgresql/ibm to v3.21.15 (#645)

Author: terraform-ibm-modules-ops

examples/advanced/main.tf

@@ -65,7 +65,7 @@ module "vpe_security_group" {
 
 module "postgresql_db" {
   source            = "terraform-ibm-modules/icd-postgresql/ibm"
-  version           = "3.21.14"
+  version           = "3.21.15"
   resource_group_id = module.resource_group.resource_group_id
   name              = "${var.prefix}-vpe-pg"
   region            = var.region