allow prod for single test letter upload

Author: masl2

scripts/utilities/letter-test-data/src/cli/index.ts

@@ -28,7 +28,8 @@ async function main() {
           demandOption: true,
           choices: [
             "820178564574", // Supplier Dev
-            "885964308133" //Supplier Nonprod
+            "885964308133", // Supplier Nonprod
+            "815459455390", // Supplier Prod
           ],
         },
         "letter-id": {