Update govuk-elements-sass to 2.2.0
Update govuk-elements-sass to 2.2.0

This release includes the custom radio button and checkbox styles.

https://github.com/alphagov/govuk_elements/blob/master/CHANGELOG.md#220

BucksCountyCouncil/verify-local-patterns,davedark/proto-timeline,samwake/hoddat-cofc-caseworking,nhsbsa/ppc-prototype,chrishanes/pvb_prisoner_proto,arminio/govuk_prototype_kit,dwpdigitaltech/hrt-prototype,paulpod/invgov,dwpdigitaltech/ejs-prototype,benjeffreys/hmcts-idam-proto,kenmaddison-scc/verify-local-patterns,abbott567/govuk_prototype_kit,Demwunz/esif-prototype,dwpdigitaltech/hrt-prototype,nhsbsa/ppc-prototype,kenmaddison-scc/verify-local-patterns,benjeffreys/hmcts-idam-proto,joelanman/govuk_prototype_kit,tsmorgan/marx,danblundell/verify-local-patterns,paulpod/invgov,Demwunz/esif-prototype,tsmorgan/marx,Demwunz/esif-prototype,dwpdigitaltech/ejs-prototype,abbott567/govuk_prototype_kit,paulpod/invgov,arminio/govuk_prototype_kit,companieshouse/ch-accounts-prototype,DilwoarH/GDS-Prototype-DM-SavedSearch,samwake/hoddat-cofc-caseworking,nhsbsa/ppc-prototype,benjeffreys/hmcts-idam-proto,danblundell/verify-local-patterns,alphagov/govuk_prototype_kit,alphagov/govuk_prototype_kit,danblundell/verify-local-patterns,abbott567/govuk_prototype_kit,BucksCountyCouncil/verify-local-patterns,gavinwye/govuk_prototype_kit,DilwoarH/GDS-Prototype-DM-SavedSearch,hannalaakso/accessible-timeout-warning,joelanman/govuk_prototype_kit,chrishanes/pvb_prisoner_proto,davedark/proto-timeline,BucksCountyCouncil/verify-local-patterns,dwpdigitaltech/ejs-prototype,tsmorgan/marx,joelanman/govuk_prototype_kit,alphagov/govuk_prototype_kit,arminio/govuk_prototype_kit,samwake/hoddat-cofc-caseworking,chrishanes/pvb_prisoner_proto,dwpdigitaltech/hrt-prototype,companieshouse/ch-accounts-prototype,hannalaakso/accessible-timeout-warning,gavinwye/govuk_prototype_kit,davedark/proto-timeline,DilwoarH/GDS-Prototype-DM-SavedSearch,hannalaakso/accessible-timeout-warning,kenmaddison-scc/verify-local-patterns