curl --request POST \
  --url https://api.leanrails.com/v1/customers/{id} \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: application/json' \
  --header 'Idempotency-Key: <idempotency-key>' \
  --data '
{
  "email": "jsmith@example.com",
  "name": "<string>",
  "phone": "<string>",
  "description": "<string>",
  "metadata": {}
}
'

{
  "id": "cus_xxx",
  "object": "customer",
  "livemode": false,
  "created": 1234567890,
  "merchant_id": "mer_xxx",
  "email": "jsmith@example.com",
  "name": "<string>",
  "phone": "<string>",
  "description": "<string>",
  "metadata": {}
}