Update run-sequence from 1.2.2 to 2.2.1
Update run-sequence from 1.2.2 to 2.2.1

Tested by ensuring that the gulp tasks in gulp/tasks.js that use run-sequence still run without error.

dwpdigitaltech/hrt-prototype,dwpdigitaltech/hrt-prototype,alphagov/govuk_prototype_kit,dwpdigitaltech/hrt-prototype,alphagov/govuk_prototype_kit,alphagov/govuk_prototype_kit