Format a time as ISO 8601 extended format
Format as ISO 8601 Basic
iex> Calendar.Time.from_erl!({20, 5, 18}) |> Calendar.Time.Format.iso8601 "20:05:18"
iex> Calendar.Time.from_erl!({20, 10, 20}) |> Calendar.Time.Format.iso_8601_basic "201020"