Local files as data for clerk's Vega-lite viewer

[j-minster]

Hi, I'm trying to show this in a clerk notebook:

(clerk/vl {:scheme "https://vega.github.io/schema/vega-lite/v5.json"
           :title {:text "Cheapest European Cities"}
           :data {:url "costs.csv"}
           :mark "bar"
           :encoding {
                      :x {:field "daily_cost" :type "quantitative" :title "Daily Cost"}
                      :y {:field "city" :type "nominal"}
                      }})

where costs.csv comes from this URL originally.

If I put the actual non-local URL instead of just costs.csv (which is saved in the same directory as my clerk notebook), it works and shows a bar chart. Do I need to do something fancy to pass a local file to :data?