Rubocop: ignore migrations from before 2020
Rubocop: ignore migrations from before 2020

There are a number of linting errors for migration files from
2016 to 2017, which cannot be fixed automatically. The time
and effort to fix, and the risk of an incorrect fix, makes it
not worth doing.

alphagov/local-links-manager,alphagov/local-links-manager,alphagov/local-links-manager