list_keys(page_size) returns 1 too many results

[daattali]

It seems like the page_size parameter is always returning one too many results.

> client <- DominoDataR::datasource_client()
> DominoDataR::list_keys(client, "mys3", page_size = 3)
[1] "Andrews_files/actual_house_prices.csv" "Andrews_files/gt_actual_pred.csv"     
[3] "Andrews_files/housing-pred-data.csv"   "Andrews_files/kc_house_data.csv"      
> DominoDataR::list_keys(client, "mys3", page_size = 6)
[1] "Andrews_files/actual_house_prices.csv" "Andrews_files/gt_actual_pred.csv"     
[3] "Andrews_files/housing-pred-data.csv"   "Andrews_files/kc_house_data.csv"      
[5] "C22760_prediction_11.csv"              "C22760_prediction_2.csv"              
[7] "Test data - GT_alphanumeric.csv"