Are tests failing on Windows?
Running the tests on windows fail:

```
>>> pytest pandas\tests\tseries\offsets\test_offsets.py -x
――――――――――――――――――――― TestCommon.test_apply[BusinessDay0] ―――――――――――――――――――――

self = <pandas.tests.tseries.offsets.test_offsets.TestCommon object at 0x066D4530>
offset_types = <class 'pandas.tseries.offsets.BusinessDay'>

    def test_apply(self, offset_types):
        sdt = datetime(2011, 1, 1, 9, 0)
        ndt = np_datetime64_compat('2011-01-01 09:00Z')

        for dt in [sdt, ndt]:
            expected = self.expecteds[offset_types.__name__]
            self._check_offsetfunc_works(offset_types, 'apply', dt, expected)

            expected = Timestamp(expected.date())
            self._check_offsetfunc_works(offset_types, 'apply', dt, expected,
>                                        normalize=True)

pandas\tests\tseries\offsets\test_offsets.py:357:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
pandas\tests\tseries\offsets\test_offsets.py:320: in _check_offsetfunc_works
    result = func(dt_tz)
pandas\tseries\offsets.py:85: in wrapper
    result = result.normalize()
pandas\_libs\tslibs\timestamps.pyx:1086: in pandas._libs.tslibs.timestamps.Timestamp.normalize
    normalized_value = normalize_i8_timestamps(
pandas\_libs\tslibs\conversion.pyx:1095: in pandas._libs.tslibs.conversion.normalize_i8_timestamps
    result = _normalize_local(stamps, tz)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

>   pos = trans.searchsorted(stamps, side='right') - 1
E   ValueError: Buffer dtype mismatch, expected 'int64_t' but got 'int'

pandas\_libs\tslibs\conversion.pyx:1151: ValueError
```

Several tests fail. 

By going back in commit history until the tests pass, it looks like this is caused by #21826.