Fix Style/OpenStructUse offenses

Changelog: other

.rubocop_todo/style/open_struct_use.yml

@@ -22,7 +22,6 @@ Style/OpenStructUse:
   - 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/features/projects/clusters_spec.rb
   - spec/finders/template_finder_spec.rb
   - spec/graphql/mutations/branches/create_spec.rb

spec/features/projects/clusters/gcp_spec.rb

@@ -49,7 +49,8 @@ RSpec.describe 'Gcp Cluster', :js do
         before do
           allow_any_instance_of(GoogleApi::CloudPlatform::Client)
             .to receive(:projects_zones_clusters_create) do
-            OpenStruct.new(
+            double(
+              'cluster',
               self_link: 'projects/gcp-project-12345/zones/us-central1-a/operations/ope-123',
               status: 'RUNNING'
             )