[PATCH 5/7] travis: test Python 3.6

[Stephen Finucane]

On Thu, 2018-01-25 at 13:43 +1100, Daniel Axtens wrote:
> We have a tox entry for py36-django111. We should test that in
> Travis CI.
> 
> Signed-off-by: Daniel Axtens <dja at axtens.net>

Reviewed-by: Stephen Finucane <stephen at that.guru>