message: [bugfix] dedup groupby columns in Deck visualizations
  When specifying the same column twice as a `Extra Data for JS` and
  `Categorical Color`, an error is issued. This addresses this issue.
diff: @@ -2036,6 +2036,7 @@ class BaseDeckGLViz(BaseViz):
  if fd.get('js_columns'):
  gb += fd.get('js_columns')
  metrics = self.get_metrics()
  + gb = list(set(gb))
  if metrics:
  d['groupby'] = gb
  d['metrics'] = self.get_metrics()
  