www/py-dj21-django-tables2: Update to 2.0.3

Notable changes since 1.21.2:

• Appearance of the paginators might be different from the current 1.x templates.
• Removed the template argument to the table constructor, use template_name instead.
• Stopped adding column names to the class attribute of table cells (<td> tags) by default.
• "verbose_names" derived from model fields are not passed through "title()" anymore, only the first character is converted to upper case. This follows Django's convention for verbose field names: "The convention is not to capitalize the first letter of the verbose_name. Django will automatically capitalize the first letter where it needs to."
• Many other bugfixes, for a full changelog see here:

https://github.com/jieter/django-tables2/blob/v2.0.3/CHANGELOG.md

Approved by: miwi (mentor)
Differential Revision: https://reviews.freebsd.org/D19159