Log Message:
py-arrow: updated to 0.15.7

0.15.7:

- [NEW] Added a number of built-in format strings. See the `docs \ 
<https://arrow.readthedocs.io/#built-in-formats>`_ for a complete list of \ 
supported formats. For example:

.. code-block:: python

    >>> arw = arrow.utcnow()
    >>> arw.format(arrow.FORMAT_COOKIE)
    'Wednesday, 27-May-2020 10:30:35 UTC'

- [NEW] Arrow is now fully compatible with Python 3.9 and PyPy3.
- [NEW] Added Makefile, tox.ini, and requirements.txt files to the distribution \ 
bundle.
- [NEW] Added French Canadian and Swahili locales.
- [NEW] Added ``humanize`` week granularity translation for Hebrew, Greek, \ 
Macedonian, Swedish, Slovak.
- [FIX] ms and μs timestamps are now normalized in ``arrow.get()``, \ 
``arrow.fromtimestamp()``, and ``arrow.utcfromtimestamp()``. For example:

.. code-block:: python

    >>> ts = 1591161115194556
    >>> arw = arrow.get(ts)
    <Arrow [2020-06-03T05:11:55.194556+00:00]>
    >>> arw.timestamp
    1591161115

- [FIX] Refactored and updated Macedonian, Hebrew, Korean, and Portuguese locales.