Channels: Replace cookie_date in sessions.py

[ShadowLNC]

In channels/sessions.py, line 13:
from django.utils.http import cookie_date

The deprecation notice is in Django 2.1 release notes (the recommended replacement is django.utils.http.http_date). Since it was deprecated in 2.1, now that stable/2.2.x has been forked, the Django master branch has had cookie_date removed, and users with the development version are no longer able to use Channels.

See also: Django commit 958a7b4c: Refs #28965 -- Removed utils.http.cookie_date() per deprecation timeline.

The following information is provided as it is requested in the template, but I don't see it being useful:

Invocation: python manage.py

Traceback (most recent call last):
  File "manage.py", line 16, in <module>
    execute_from_command_line(sys.argv)
  File "d:\professional\firstinspires\fll-scoring\fllfms\venv\src\django\django\core\management\__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "d:\professional\firstinspires\fll-scoring\fllfms\venv\src\django\django\core\management\__init__.py", line 357, in execute
    django.setup()
  File "d:\professional\firstinspires\fll-scoring\fllfms\venv\src\django\django\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "d:\professional\firstinspires\fll-scoring\fllfms\venv\src\django\django\apps\registry.py", line 122, in populate
    app_config.ready()
  File "D:\Professional\firstinspires\fll-scoring\fllfms\fllfms\apps.py", line 9, in ready
    from . import signals  # Bind signals.
  File "D:\Professional\firstinspires\fll-scoring\fllfms\fllfms\signals.py", line 6, in <module>
    from .consumers import TimerConsumer
  File "D:\Professional\firstinspires\fll-scoring\fllfms\fllfms\consumers.py", line 7, in <module>
    from channels.auth import get_user
  File "D:\Professional\firstinspires\fll-scoring\fllfms\venv\lib\site-packages\channels\auth.py", line 19, in <module>
    from channels.sessions import CookieMiddleware, SessionMiddleware
  File "D:\Professional\firstinspires\fll-scoring\fllfms\venv\lib\site-packages\channels\sessions.py", line 13, in <module>
    from django.utils.http import cookie_date
ImportError: cannot import name 'cookie_date'

System:

Python 3.6.6 x64, Windows 10 (x64) Education, version 1809 (build 17763.194).

$ pip freeze
asgiref==2.3.2
async-timeout==3.0.1
attrs==18.2.0
autobahn==18.12.1
Automat==0.7.0
channels==2.1.6
constantly==15.1.0
cx-Freeze==5.1.1
daphne==2.2.4
-e git+https://github.com/django/django@bff748df3e1e1c0077e02df2b77bda2b827ad129#egg=Django
django-reversion==3.0.2
hyperlink==18.0.0
idna==2.8
incremental==17.5.0
Nuitka==0.6.1
PyHamcrest==1.9.0
pytz==2018.5
pywin32==224
six==1.12.0
sqlparse==0.2.4
Twisted==18.9.0
txaio==18.8.1
tzlocal==1.5.1
zope.interface==4.6.0

[carltongibson]

Hi @ShadowLNC. This looks right. A PR switching to http_date would be great!