gh-128074: Add support `+HH` format as time zone in `datetime.strptime`

[donbarbos]

I made the minute (MM) part optional for time zone.

New behavior:

>>> from datetime import datetime
>>> datetime.strptime("2023-05-25T15:35:05.666+11", "%Y-%m-%dT%H:%M:%S.%f%z")
datetime.datetime(2023, 5, 25, 15, 35, 5, 666000, tzinfo=datetime.timezone(datetime.timedelta(seconds=39600)))

Old behavior:

>>> from datetime import datetime
>>> datetime.strptime("2023-05-25T15:35:05.666+11", "%Y-%m-%dT%H:%M:%S.%f%z")
Traceback (most recent call last):
  File "<python-input-2>", line 1, in <module>
    datetime.strptime("2023-05-25T15:35:05.666+11", "%Y-%m-%dT%H:%M:%S.%f%z")
    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../cpython/Lib/_strptime.py", line 700, in _strptime_datetime_datetime
    tt, fraction, gmtoff_fraction = _strptime(data_string, format)
                                    ~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File ".../cpython/Lib/_strptime.py", line 453, in _strptime
    raise ValueError("time data %r does not match format %r" %
                     (data_string, format))
ValueError: time data '2023-05-25T15:35:05.666+11' does not match format '%Y-%m-%dT%H:%M:%S.%f%z'

• Issue: gh-128074

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