curl --request GET \
  --url https://sandbox.withclasp.com/plan_configurations \
  --header 'Authorization: Bearer <token>'

{
  "next": "<string>",
  "previous": "<string>",
  "results": [
    {
      "id": "<string>",
      "plan": "<string>",
      "waiting_period": {
        "id": "<string>",
        "duration": 123,
        "allow_coinciding_start": true
      },
      "required_subclass": "<string>",
      "dependent_age_limit": 123,
      "base_plan_configuration": "<string>"
    }
  ]
}