e_treemap() drillDownIcon duplicated

[thesixmax]

Hi and thanks for a great package!

I noticed something odd when trying out different options for e_treemap() using the echarts documentation as a reference. If I use the df from your page and run the following:

df %>%
  e_charts() %>%
  e_treemap(leafDepth = 1,
            drillDownIcon = '▶')

then I end up with the drillDownIcon being shown as ▶▶ on the plot and not ▶ as I expected. I am not sure whether this is due to something on my end or if it is related to the package. It is by no means a big deal, but thought that I should mention it anyway.

[swsoyee]

It should be fixed after bump the ECharts version to the latest.
apache/echarts#14299