message: refactor(serverless-next.js): Add `let` to iteration in `default-lambda-handler`
  Removes the warning viewing in the lambda console.
  Using `let` to match although I think both can be `const`?
diff: @@ -13,7 +13,7 @@ const router = manifest => {
  return ssr.nonDynamic[path];
  }
  - for (route in allDynamicRoutes) {
  + for (let route in allDynamicRoutes) {
  const { file, regex } = allDynamicRoutes[route];
  const re = new RegExp(regex, "i");
  