Get list of project variables

curl --request GET \
  --url {schemes}://api.upsun.com/projects/{projectId}/variables \
  --header 'Authorization: Bearer <token>'

[
  {
    "id": "<string>",
    "created_at": "2023-11-07T05:31:56Z",
    "updated_at": "2023-11-07T05:31:56Z",
    "name": "<string>",
    "attributes": {},
    "is_json": true,
    "is_sensitive": true,
    "visible_build": true,
    "visible_runtime": true,
    "application_scope": [
      "<string>"
    ],
    "value": "<string>"
  }
]