Fix field name extraction in parse_payload to handle list types

[hmueller01]

With my current Python 3.13 I get an error

  File "resol-vbus-python/resol.py", line 164, in parse_payload
    result[get_source_name(msg)][field['name']] = \
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
TypeError: unhashable type: 'list'

as spec file can be

       "field": [
          {
            "offset": "0",
            "name": [
              "Temperatur Sensor 1",
              {
                "-lang": "en",
                "#text": "Temperature sensor 1"
              }
            ],
            "bitSize": "15",
            "factor": "0.1",
            "unit": " °C"
          },

or

        "field": [
          {
            "-commonUsage": "'collector1'",
            "offset": "0",
            "name": "Temperatur Sensor 1",
            "bitSize": "15",
            "factor": "0.1",
            "unit": " \\u00b0C"
          },