message: use URLSearchParams for Reports endpoint
diff: +import { URLSearchParams } from 'url';
  import { OAuthClient, IOAuthClient } from './OAuthClient';
  import { Invoice, ContactGroup, ContactGroupsResponse, InvoicesResponse, CurrenciesResponse, Currency, ContactsResponse, AccountsResponse, Employee, EmployeesResponse, ReportsResponse } from './interfaces/AccountingResponse';
  @@ -249,14 +250,11 @@ export class XeroAPIClient {
  get: async (args?: any): Promise<ReportsResponse> => {
  let endpoint = 'Reports';
  if (args) {
  - // TODO construct query string in a shared function
  - const query = Object.keys(args).map((key: string) => {
  - if (key != 'ReportID' && key != 'Accept') {
  - return key + '=' + args[key];
  - }
  - }).filter((x) => x).join('&');
  + const query = new URLSearchParams(args);
  + query.delete('Accept');
  + query.delete('ReportID');
  - endpoint = endpoint + '/' + args.ReportID + '?' + query;
  + endpoint = endpoint + '/' + args.ReportID + '?' + query.toString();
  }
  return this.get<ReportsResponse>(endpoint, args);
  