Update govuk_seed_crawler gem
Update govuk_seed_crawler gem

This updates the seed crawler gem to version 3.1.0 and updates the Ruby
version used to the current latest one (3.1.2) as 2.6.3 is end-of-life.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet