getCampus method
Will get a collection of PcoGivingCampus objects (expecting one)
using a path like this: https://api.planningcenteronline.com/giving/v2/donations/1/campus
Implementation
Future<PcoCollection<PcoGivingCampus>> getCampus(
{PcoGivingCampusQuery? query}) async {
query ??= PcoGivingCampusQuery();
var url = '$apiEndpoint/campus';
return PcoCollection.fromApiCall<PcoGivingCampus>(url,
query: query, apiVersion: apiVersion);
}