Use ruby 2.6.3 on CI
Use ruby 2.6.3 on CI

KnapsackPro/rails-app-with-knapsack_pro,KnapsackPro/rails-app-with-knapsack_pro,KnapsackPro/rails-app-with-knapsack_pro,KnapsackPro/rails-app-with-knapsack_pro