Add clean_channel method

[fosterseth]

requires this django PR https://github.com/django/channels/pull/1948

addresses memory leak issue https://github.com/django/channels_redis/issues/276

[acu192]

See my other comment I just made: https://github.com/django/channels/pull/1948#issuecomment-1312165651

I do have permissions in this repo, so I ran the workflows for you.

My only comment is to update or delete this comment.

[fosterseth]

@acu192 thank you for taking a look!