Added OFF to FanMode for STARKVIND air purifier

[slajob]

Based on json dump from @BeauGiles, OFF value occurs

    {
        'id': '979e33c7-2d25-458a-9178-1bcac4e06b77_1',
        'type': 'airPurifier',
        'deviceType': 'airPurifier',
        'createdAt': '2023-01-21T16: 44: 36.000Z',
        'isReachable': True,
        'lastSeen': '2024-03-25T07: 45: 49.000Z',
        'attributes': {
            'customName': 'Airpurifier1',
            'model': 'STARKVINDAirpurifiertable',
            'manufacturer': 'IKEAofSweden',
            'firmwareVersion': '1.1.001',
            'hardwareVersion': '1',
            'serialNumber': 'XXXXXXXXXXXXXXXXX',
            'productCode': 'E2006',
            'fanMode': 'off',
            'fanModeSequence': 'lowMediumHighAuto',
            'motorState': 0,
            'motorRuntime': 396238,
            'filterElapsedTime': 116489,
            'filterAlarmStatus': False,
            'filterLifetime': 259200,
            'childLock': False,
            'statusLight': True,
            'currentPM25': 0,
            'identifyStarted': '2000-01-01T00: 00: 00.000Z',
            'identifyPeriod': 0,
            'permittingJoin': False,
            'otaStatus': 'upToDate',
            'otaState': 'readyToCheck',
            'otaProgress': 0,
            'otaPolicy': 'autoUpdate',
            'otaScheduleStart': '00: 00',
            'otaScheduleEnd': '00: 00'
        },
        'capabilities': {
            'canSend': [

            ],
            'canReceive': [
                'customName',
                'fanMode',
                'fanModeSequence',
                'motorState',
                'childLock',
                'statusLight'
            ]
        },
        'room': {
            'id': 'd89b082e-e2c8-4898-81b6-e952b0e5ab7d',
            'name': 'DiningRoom',
            'color': 'ikea_yellow_no_24',
            'icon': 'rooms_arm_chair'
        },
        'deviceSet': [

        ],
        'remoteLinks': [

        ],
        'isHidden': False
    }