test_summary will fail in Pandas3

[berland]

In Pandas3 the tests will not pass due to:

    def test_df2ressum(dframe):
        """Test that a dataframe can be converted to a summary object, and then read
        back again"""
    
        # Massage the dframe first so we can assert on equivalence after.
        dframe = _fix_dframe_for_resdata(dframe)
    
        summary = df2ressum(dframe)
        if dframe.empty:
            assert summary is None
            return
    
        dframe_roundtrip = df(summary)
>       pd.testing.assert_frame_equal(
            dframe.sort_index(axis=1),
            dframe_roundtrip.sort_index(axis=1),
            check_dtype=False,
        )

tests/test_summary.py:1037: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

left = Index([2016-01-01 00:00:00], dtype='object', name='DATE'), right = DatetimeIndex(['2016-01-01'], dtype='datetime64[us]', name='DATE', freq=None), obj = 'DataFrame.index'

    def _check_types(left, right, obj: str = "Index") -> None:
        if not exact:
            return
    
>       assert_class_equal(left, right, exact=exact, obj=obj)
E       AssertionError: DataFrame.index are different
E       
E       DataFrame.index classes are different
E       [left]:  Index([2016-01-01 00:00:00], dtype='object', name='DATE')
E       [right]: DatetimeIndex(['2016-01-01'], dtype='datetime64[us]', name='DATE', freq=None)

/data/venv/venv/lib64/python3.11/site-packages/pandas/_testing/asserters.py:245: AssertionError
======================================================================================= short test summary info =======================================================================================
FAILED tests/test_summary.py::test_df2ressum[dframe1] - AssertionError: DataFrame.index are different

[berland]

This is related to a FutureWarning that Pandas 2.2.3 is emitting:

/data/venv/venv/lib64/python3.11/site-packages/pandas/core/indexes/base.py:7588: FutureWarning: Dtype inference on a pandas object (Series, Index, ExtensionArray) is deprecated. The Index constructor will keep the original dtype in the future. Call `infer_objects` on the result to get the old behavior.
  return Index(sequences[0], name=names)