Multidict: Reference leak in CIMultiDict/MultiDict items-view union and subtraction

{
                    "vendor": "aio-libs",
                    "product": "multidict",
                    "versions": [
                        {
                            "version": ">= 6.7.0, < 6.9.1",
                            "status": "affected"
                        }
                    ]
                }