Fix the accuracy for specific problem

Author: cloudboat

pandas/core/arrays/datetimelike.py

@@ -1656,7 +1656,7 @@ def mean(self, *, skipna: bool = True, axis: AxisInt | None = 0):
         >>> tdelta_idx = pd.to_timedelta([1, 2, 3], unit="D")
         >>> tdelta_idx
         TimedeltaIndex(['1 days', '2 days', '3 days'],
-                        dtype='timedelta64[us]', freq=None)
+                        dtype='timedelta64[ns]', freq=None)
         >>> tdelta_idx.mean()
         Timedelta('2 days 00:00:00')
         """