curl --request GET \
  --url https://api.sandbox.tesouro.com/finops/v1/mail-templates/system \
  --header 'Authorization: Bearer <token>' \
  --header 'x-finops-version: <x-finops-version>'

{
  "data": [
    {
      "available_templates": [
        {
          "body_template": "<string>",
          "language": "<string>",
          "subject_template": "<string>"
        }
      ],
      "template_name": "<string>"
    }
  ]
}