Tests on master are failing with latest rubocop

[andyw8]

On a fresh checkout there are many failures such as:

An error occurred while RSpec/FactoryBot/CreateList cop was inspecting /Users/andyw8/src/github.com/rubocop-hq/rubocop-rails/spec/rubocop/cop/rails/not_null_column_spec.rb:89:8.
To see the complete backtrace run rubocop -d.

rubocop/rubocop#8490 seems to be the cause, it passes with the commit prior to that.

[bbatsov]

Yes, that's true. We already discussed this with @bquorning and co in the past and agreed to make this change right before RuboCop 1.0, so extensions can quickly adopt it afterwards.