Retrieve a plan

curl --request GET \
  --url https://api.spacebring.com/plans/v1/{id} \
  --header 'Authorization: Basic <encoded-value>'

{
  "plan": {
    "createDate": "2023-11-07T05:31:56Z",
    "credits": 123,
    "customTax": {
      "enabled": true,
      "rate": 123
    },
    "dayPasses": 123,
    "description": "<string>",
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "locationRef": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "period": "day",
    "price": 123,
    "selfSignup": {
      "enabled": true,
      "type": "immediate"
    },
    "title": "<string>"
  }
}