www/py-dj21-django-tables2: Update to 2.0.6

Changes since 2.0.3:

• Add optional 'table' kwarg to row_attrs callables.
• Fixed issue with wrong time format for TimeColumn.
• The "ValueError" raised if the QuerySet passed to a table instance did not match the value declared in Meta.model is now turned into a warning.
• Make sure the templates do not raise errors when thead/tfoot attributes are not defined.

https://github.com/jieter/django-tables2/blob/v2.0.6/CHANGELOG.md

Approved by: mentors (implicit)