List saved payment methods (Stripe `pm_*` references)

curl -X GET https://api.moonborn.co/v1/billing/payment_methods \
  -H "Authorization: Bearer $MOONBORN_API_KEY"

import Moonborn from '@moonborn/sdk';

const client = new Moonborn({ apiKey: process.env.MOONBORN_API_KEY });

const result = await client.billing.listPaymentMethods();

import os
from moonborn import Moonborn

client = Moonborn(api_key=os.environ["MOONBORN_API_KEY"])

result = client.billing.list_payment_methods()