add finance app to istio [ci skip]

modules/kubernetes/finance_app/main.tf

@@ -13,6 +13,9 @@ variable "gocardless_secret_id" {}
 resource "kubernetes_namespace" "finance_app" {
   metadata {
     name = "finance-app"
+    labels = {
+      "istio-injection" : "enabled"
+    }
   }
 }