Redmine Project Types Relations

GitHub tests are failing due to an ActiveModel::UnknownAttributeError: unknown error. It complains

Error:
ProjectTypesRelations::ProjectTypePatchTest#test_should_not_save_itself_as_subordinate_relation:
NoMethodError: undefined method `is_project_type=' for #<ProjectType id: 1, name: "eCookbook", description: "Recipes management application", homepage: "http://ecookbook.somenet.foo/", is_public: true, parent_id: nil, created_on: "2006-07-19 17:13:59.000000000 +0000", updated_on: "2006-07-19 20:53:01.000000000 +0000", identifier: "ecookbook", status: 1, lft: 1, rgt: 10, inherit_members: false, default_version_id: nil, default_assigned_to_id: nil, default_issue_query_id: nil>
Did you mean?  project_type=
    plugins/redmine_project_types_relations/test/project_type_creator.rb:30:in `find_project_type'
    plugins/redmine_project_types_relations/test/unit/project_type_patch_test.rb:68:in `project_type'
    plugins/redmine_project_types_relations/test/unit/project_type_patch_test.rb:43:in `block in <class:ProjectTypePatchTest>'

rails test plugins/redmine_project_types_relations/test/unit/project_type_patch_test.rb:42

See https://github.com/xmera-circle/redmine_project_types_relations/actions/workflows/5-0-stable.yml for details.