List templates

curl --request GET \
  --url https://vortexpdf.com/api/v1/templates \
  --header 'Authorization: Bearer <token>'

{
  "data": [
    {
      "content": "<h1>Invoice</h1><p>This is a sample invoice template</p>",
      "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
      "inserted_at": "2020-01-01T00:00:00Z",
      "name": "Invoice Template",
      "preview_context": {
        "amount": 1000,
        "customer": "Acme Inc."
      },
      "updated_at": "2020-01-01T00:00:00Z"
    }
  ]
}