Ошибка при вызове метода json.loads()

при вызове метода loads у json у меня возникает ошибка:

json.decoder.JSONDecodeError: Expecting property name enclosed in double quotes: line 1 column 2 (char 1)

код:

test_data = {
                "formatVersion": 1,
                "creationTimeStamp": "2022-04-22T12:56:11+03:00",
                "dataTimeStamp": "2022-04-22T11:56:13+02:00",
                "creator": "SRS 3.8.0",
                "project": "DANI",
                "specialTexts": [{
                    "id": 2,
                    "text": [{
                        "text": "special text 1",
                        "language": "xx"
                    }]
                }, {
                    "id": 3,
                    "text": [{
                        "text": "special text 2",
                        "language": "xx"
                    }]
                }, {
                    "id": 4,
                    "text": [{
                        "text": "",
                        "language": "xx"
                    }]
                }],
                "trips": [{
                    "id": "INTERVAL",
                    "departure": "2022-04-21T08:03:00+02:00",
                    "coaches": [{
                        "id": "1",
                        "spots": [{
                            "id": "1",
                            "from": "0",
                            "to": "5",
                            "specialText": 1
                        }, {
                            "id": "2",
                            "from": "0",
                            "to": "6",
                            "specialText": 2
                        }, {
                            "id": "3",
                            "from": "0",
                            "to": "11",
                            "specialText": 3
                        }, {
                            "id": "4",
                            "from": "0",
                            "to": "11",
                            "specialText": 1
                        }, {
                            "id": "5",
                            "from": "0",
                            "to": "10",
                            "specialText": 2
                        }, {
                            "id": "6",
                            "from": "0",
                            "to": "11",
                            "specialText": 3
                        }]
                    }]
                }]
            }
        a = json.loads(str(test_data))