Update boilerplate models

[spsanderson]

Update boilerplate models with the following:

Current:

# Make final workflow
        wflw_fit <- wflw %>%
            tune::finalize_workflow(
                tuned_results %>%
                    tune::show_best(metric = best_metric, n = Inf) %>%
                    dplyr::slice(1)
            ) %>%
            parsnip::fit(rsample::training(splits))

Future:

# Make final workflow
        wflw_fit <- wflw %>%
            tune::finalize_workflow(
                tuned_results %>%
                    tune::show_best(metric = best_metric, n = 1)
            ) %>%
            parsnip::fit(rsample::training(splits))