Add new line to cmdio JSON rendering (#443)

## Changes
This PR adds a new line break to JSON rendering using cmdio. This is
useful when we call `cmdio.Render` multiple times

## Tests
Manually

Co-authored-by: Pieter Noordhuis <pieter.noordhuis@databricks.com>

libs/cmdio/render.go

@@ -50,6 +50,10 @@ func renderJson(w io.Writer, v any) error {
 		return err
 	}
 	_, err = w.Write(pretty)
+	if err != nil {
+		return err
+	}
+	_, err = w.Write([]byte("\r\n"))
 	return err
 }