ensure article published dates are far enough apart to ensure they are sorted properly (#6811)

spec/system/articles/user_visits_an_article_spec.rb

@@ -52,6 +52,7 @@ RSpec.describe "Views an article", type: :system do
     context "with regular articles" do
       it "lists the articles in ascending published_at order" do
         articles = create_list(:article, 2)
+        articles.first.update(published_at: 1.week.ago)
         articles.each { |a| a.update_columns(collection_id: collection.id) }
 
         visit articles.first.path