Revert "Update nokogiri to 1.8.5 following security warning"
Revert "Update nokogiri to 1.8.5 following security warning"

This reverts commit b08499a6dfcf4c003d9a3288ad14b7f87c968bf7.

nhsconnect/gpconnect,nhsconnect/gpconnect,nhsconnect/gpconnect