Fix bundler audit in production
Fix bundler audit in production

When `bundle exec rake` runs it loads all of the rake tasks.

Because `bundler-audit` is only included in development and test
environments, this causes all Rake tasks to fail on production.

Moving the require into the task fixes this.

bitzesty/trade-tariff-backend,alphagov/trade-tariff-backend,leftees/trade-tariff-backend,leftees/trade-tariff-backend,bitzesty/trade-tariff-backend,leftees/trade-tariff-backend,alphagov/trade-tariff-backend,alphagov/trade-tariff-backend,bitzesty/trade-tariff-backend