F# json.net deserialize

d.fs

namespace PoeIngester
open HttpFs.Client
open System.Net.Http
open Hopac
open Newtonsoft.Json

module Bookmark =
    type responseBody = {
        [<JsonProperty(PropertyName="next_change_id")>]
        NextChangeId: string;
    }

    let apiUrl = "https://poe.ninja/api/Data/GetStats"
    let fetch (client: HttpClient) = job {
            let request = Request.createWithClient client Get (System.Uri(apiUrl))

            use! response = getResponse request
            let! body = Response.readBodyAsString response
            let rb = JsonConvert.DeserializeObject<responseBody>(body)

            return rb.NextChangeId
        }