fix: django conf should not be modified

[techblack]

This place is passed by reference, which will cause the configuration to change, and other applications will read the wrong configuration

before this pr:
from django.conf import settings getattr(settings, "CHANNEL_LAYERS", {})
result

{'default': {'BACKEND': 'channels_redis.core.RedisChannelLayer', 'CONFIG': {'hosts': [{'sentinels': [('a.b.c.d', 6379)], 'master_name': 'redis-master', 'db': 0, 'password': 'password', 'sentinel_kwargs': {'password': 'password'}}]}}}

after channel connection result

{'default': {'BACKEND': 'channels_redis.core.RedisChannelLayer', 'CONFIG': {'hosts': [{'db': 0, 'password': 'password'}]}}}

[krisatverbidio]

Also affected by this bug. Would love to see this get merged in soon.

[carltongibson]

I'm planning releases for the new year period. This is on the agenda for that.

[sevdog]

This should work like pubsub layer, if a deepcopy is realy needed it should also be addressed also in that layer.

[carltongibson]

Resolved in #352. Thanks.