Fix OpenStruct use in board_lists_resolver

.rubocop_todo/style/open_struct_use.yml

@@ -5,7 +5,6 @@ Style/OpenStructUse:
   - ee/spec/db/production/license_spec.rb
   - ee/spec/features/projects/new_project_spec.rb
   - ee/spec/finders/template_finder_spec.rb
-  - ee/spec/graphql/ee/resolvers/board_lists_resolver_spec.rb
   - ee/spec/helpers/ee/blob_helper_spec.rb
   - ee/spec/lib/gitlab/auth/group_saml/failure_handler_spec.rb
   - ee/spec/lib/gitlab/legacy_github_import/project_creator_spec.rb

ee/spec/graphql/ee/resolvers/board_lists_resolver_spec.rb

@@ -50,7 +50,7 @@ RSpec.describe Resolvers::BoardListsResolver do
 
   def resolve_board_lists(args: {}, current_user: user)
     context = GraphQL::Query::Context.new(
-      query: OpenStruct.new(schema: nil),
+      query: double('query', schema: nil),
       values: { current_user: current_user },
       object: nil
     )