Merge pull request #16 from marcus-deans/main

Fix stacked bar chart

Author: igorkasyanchuk

lib/rails_charts/stacked_bar_chart.rb

@@ -4,7 +4,7 @@ class StackedBarChart < BarChart
     def defaults
       super.deep_merge({
         series: {
-          stack: {}        
+          stack: 'stack',
         },
       })
     end