CI: Failing NumpyDev
https://github.com/pandas-dev/pandas/runs/2985248923
```
=================================== FAILURES ===================================
__________ TestTimedeltaMultiplicationDivision.test_td_div_nan[nan1] ___________
[gw0] linux -- Python 3.9.5 /usr/share/miniconda/envs/pandas-dev/bin/python

self = <pandas.tests.scalar.timedelta.test_arithmetic.TestTimedeltaMultiplicationDivision object at 0x7f2d87ba9f40>
nan = nan

    @pytest.mark.parametrize(
        "nan",
        [
            np.nan,
            pytest.param(
                np.float64("NaN"),
                marks=pytest.mark.xfail(
                    # Works on numpy dev only in python 3.9
                    is_numpy_dev and not compat.PY39,
                    raises=RuntimeWarning,
                    reason="https://github.com/pandas-dev/pandas/issues/31992",
                ),
            ),
            float("nan"),
        ],
    )
    def test_td_div_nan(self, nan):
        # np.float64('NaN') has a 'dtype' attr, avoid treating as array
        td = Timedelta(10, unit="d")
        result = td / nan
        assert result is NaT
    
>       result = td // nan

pandas/tests/scalar/timedelta/test_arithmetic.py:455: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

>   return Timedelta(self.value // other, unit='ns')
E   RuntimeWarning: invalid value encountered in double_scalars

pandas/_libs/tslibs/timedeltas.pyx:1465: RuntimeWarning
```