Downgrade nokogiri
Downgrade nokogiri

Because it uses a higher version of ruby than we use in our CI.
This should be resolved after TMA-279.

Seikitsu/gooddata-ruby,vhtien/gooddata-ruby,Seikitsu/gooddata-ruby,vhtien/gooddata-ruby,Seikitsu/gooddata-ruby,vhtien/gooddata-ruby