API/BUG: hashing of datetimes is based on UTC values
These should are 3 different 'views' of the same time. We DO disambiguate these in mains. So we should do so when hashing as well.

xref #16346 

```
In [1]: from pandas.util import hash_pandas_object

In [8]: hash_pandas_object(pd.date_range('20130101', periods=3, tz='UTC').tz_convert('US/Eastern'))
Out[8]: 
2012-12-31 19:00:00-05:00     4326795898974544501
2013-01-01 19:00:00-05:00     2833560015380952180
2013-01-02 19:00:00-05:00    14913883737423839247
Freq: D, dtype: uint64

In [9]: hash_pandas_object(pd.date_range('20130101', periods=3, tz='UTC'))
Out[9]: 
2013-01-01 00:00:00+00:00     4326795898974544501
2013-01-02 00:00:00+00:00     2833560015380952180
2013-01-03 00:00:00+00:00    14913883737423839247
Freq: D, dtype: uint64

In [10]: hash_pandas_object(pd.date_range('20130101', periods=3))
Out[10]: 
2013-01-01     4326795898974544501
2013-01-02     2833560015380952180
2013-01-03    14913883737423839247
Freq: D, dtype: uint64

```