getSeries method
Will get a collection of PcoServicesSeries objects (expecting many)
using a path like this: https://api.planningcenteronline.com/services/v2/series
Implementation
Future<PcoCollection<PcoServicesSeries>> getSeries(
{PcoServicesSeriesQuery? query}) async {
query ??= PcoServicesSeriesQuery();
var url = '$apiEndpoint/series';
return PcoCollection.fromApiCall<PcoServicesSeries>(url,
query: query, apiVersion: apiVersion);
}