python-chess v1.2.1

The primary location for the published package is now
https://pypi.org/project/chess/. Thanks to
`Kristian Glass <https://github.com/doismellburning>`_ for transferring the
namespace.

The old https://pypi.org/project/python-chess/ will remain an alias that
installs the package from the new location as a dependency (as recommended by
`PEP423 <https://www.python.org/dev/peps/pep-0423/#how-to-rename-a-project>`_).