DEV: remove update_attributes which is deprecated in Rails 6

See: https://github.com/rails/rails/pull/31998

update_attributes is a relic of the past, it should no longer be used.

spec/tasks/posts_spec.rb

@@ -45,7 +45,7 @@ RSpec.describe "Post rake tasks" do
 
   describe 'rebake_match' do
     it 'rebakes matched posts' do
-      post.update_attributes(cooked: '')
+      post.update(cooked: '')
 
       HighLine::Simulate.with('y') do
         Rake::Task['posts:rebake_match'].invoke('brown')