new windows pip-pre test failures

[drammock]

tuple-vs-list failures. https://dev.azure.com/mne-tools/mne-python/_build/results?buildId=29144&view=logs&j=dded70eb-633c-5c42-e995-a7f8d1f99d91&t=d18f7f2f-13af-5901-1cbc-7fa039d0db3a&l=4001

FAILED mne/tests/test_epochs.py::test_to_data_frame_index[time] - AssertionError: assert ('time',) == ['time']
FAILED mne/tests/test_epochs.py::test_to_data_frame_index[index1] - AssertionError: assert ('condition', 'time', 'epoch') == ['condition', 'tim...
FAILED mne/tests/test_epochs.py::test_to_data_frame_index[index2] - AssertionError: assert ('epoch', 'time') == ['epoch', 'time']
FAILED mne/tests/test_epochs.py::test_to_data_frame_index[index3] - AssertionError: assert ('time', 'epoch') == ['time', 'epoch']
FAILED mne/tests/test_epochs.py::test_to_data_frame_index[None] - assert (None,) == [None]
FAILED mne/tests/test_source_estimate.py::test_to_data_frame_index[time] - AssertionError: assert ('time',) == ['time']
FAILED mne/tests/test_source_estimate.py::test_to_data_frame_index[index1] - AssertionError: assert ('time', 'subject') == ['time', 'subject']
FAILED mne/tests/test_source_estimate.py::test_to_data_frame_index[None] - assert (None,) == [None]
FAILED mne/time_frequency/tests/test_tfr.py::test_to_data_frame_index[time] - AssertionError: assert ('time',) == ['time']
FAILED mne/time_frequency/tests/test_tfr.py::test_to_data_frame_index[index1] - AssertionError: assert ('condition', 'time', 'freq') == ['condition', 'time...
FAILED mne/time_frequency/tests/test_tfr.py::test_to_data_frame_index[index2] - AssertionError: assert ('freq', 'time') == ['freq', 'time']
FAILED mne/time_frequency/tests/test_tfr.py::test_to_data_frame_index[index3] - AssertionError: assert ('time', 'freq') == ['time', 'freq']
FAILED mne/time_frequency/tests/test_tfr.py::test_to_data_frame_index[None] - assert (None,) == [None]

first appeared in #12431