Revert "DDPB-1125 - upgrades: ruby -> 2.4  gems sass -> 3.4.25, scss_lint -> 0.54.0"
Revert "DDPB-1125 - upgrades: ruby -> 2.4  gems sass -> 3.4.25, scss_lint -> 0.54.0"

This reverts commit 7b3b19103778be19b680b40474fdcd5c181aa5f6.

ministryofjustice/opg-digi-deps-client,ministryofjustice/opg-digi-deps-client,ministryofjustice/opg-digi-deps-client,ministryofjustice/opg-digi-deps-client