Fix Style/OpenStructUse offenses

Changelog: other

.rubocop_todo/style/open_struct_use.yml

@@ -19,7 +19,6 @@ Style/OpenStructUse:
   - spec/controllers/import/fogbugz_controller_spec.rb
   - spec/controllers/import/gitlab_controller_spec.rb
   - spec/controllers/projects/clusters_controller_spec.rb
-  - spec/dependencies/omniauth_saml_spec.rb
   - spec/factories/go_module_versions.rb
   - spec/factories/wiki_pages.rb
   - spec/features/projects/clusters/gcp_spec.rb

spec/dependencies/omniauth_saml_spec.rb

@@ -7,7 +7,7 @@ RSpec.describe 'processing of SAMLResponse in dependencies' do
   let(:mock_saml_response) { File.read('spec/fixtures/authentication/saml_response.xml') }
   let(:saml_strategy) { OmniAuth::Strategies::SAML.new({}) }
   let(:session_mock) { {} }
-  let(:settings) { OpenStruct.new({ soft: false, idp_cert_fingerprint: 'something' }) }
+  let(:settings) { double('settings', { soft: false, idp_cert_fingerprint: 'something' }) }
   let(:auth_hash) { Gitlab::Auth::Saml::AuthHash.new(saml_strategy) }
 
   subject { auth_hash.authn_context }