Series arithmetic methods accepting a Timedelta should also accept a np.timedelta64

[gandhis1]

import numpy as np
import pandas as pd

s1 = pd.Series(data=pd.date_range("1/1/2020", "2/1/2020"))
s2 = pd.Series(data=pd.date_range("1/1/2021", "2/1/2021"))
s3 = (s1 - s2) / np.timedelta64(1, "M")  # pd.Series[float]

error: No overload variant of "__truediv__" of "Series" matches argument type "timedelta64" [operator]

This applies to most arithmetic methods that accept a Timedelta

[Dr-Irv]

There's a couple of issues here. One is that we do need to add np.timedetla64 as accepted in different arithmetic methods for Series. But we should also add a __truediv__() method for TimestampSeries, as well as the other arithmetic operators that accept either a pd.Timedelta or np.timedelta64