Log Message:
Update textproc/py-xlsxwriter to 0.9.6.

Release 0.9.6 - Dec 26 2016
---------------------------

* Fix for table with data but without a header.

* Add a warning when the number of series in a chart exceeds Excel's limit
  of 255.

Release 0.9.5 - Dec 24 2016
---------------------------

* Fix for missing `remove_timezone` option in Chart class.

Release 0.9.4 - Dec 2 2016
--------------------------

* Added user definable removal of timezones in datetimes. See the
  :func:`Workbook` constructor option ``remove_timezone`` and :ref:`Timezone
  Handling in XlsxWriter <timezone_handling>`.

* Fix duplicate header warning in :func:`add_table` when there is only one
  user defined header.

* Fix for `center_across` property in :func:`add_format`.