Bump govuk frontend toolkit to 4.9.1
Bump govuk frontend toolkit to 4.9.1

- Fix the phase banner alignment

alphagov/govuk_elements,gavboulton/govuk_elements,alphagov/govuk_elements,gavboulton/govuk_elements,gavboulton/govuk_elements,joelanman/govuk_elements,gavboulton/govuk_elements,alphagov/govuk_elements,joelanman/govuk_elements,alphagov/govuk_elements