It looks like you're using an older Stripe key. In order to use this API, you'll need to use a modern API key, which is prefixed with 'pk_live_' or 'pk_test_'. You can roll your publishable key here: https://dashboard.stripe.com/account/apikeysIt looks like you're using an older Stripe key. In order to use this API, you'll need to use a modern API key, which is prefixed with 'pk_live_' or 'pk_test_'. You can roll your publishable key here: https://dashboard.stripe.com/account/apikeys