pytest 3.6 support

[ostcar]

I am new to pytest, so maybe I misunderstand something.

I installed your plugin and got:

...
TERNALERROR>   File ".../site-packages/pytest_django_ordering/plugin.py", line 13, in get_marker_transaction
INTERNALERROR>     return marker.transaction
INTERNALERROR> AttributeError: 'MarkInfo' object has no attribute 'transaction'

I could fix this by replacing marker.transaction with marker.kwargs['transaction']

[rlucioni]

Thanks for the heads-up @ostcar. Assuming that change also works for older versions of pytest, I'd be happy to accept a PR.

[rlucioni]

@ostcar just wanted to let you know that this has been fixed.