Unpin channels-redis (#15329) (#6647)

* unpin channels-redis

The bug that initially caused the upgrade block has been resolved https://github.com/django/channels_redis/issues/332

* replace aioredis Exception with a redis Exception

Version 4.0.0 of channel-redis migrated the underlying Redis library from aioredis to redis-py. The Exception has been changed to an equivalent

* remove unused license

* remove UPGRADE BLOCKER in README

* remove hiredis

it was an indirect dependency from aioredis which was removed

* remove unused license

* add back hiredis

it's potentially providing a performance boost. install explicitly as a part of redis. upgrade to more recent version

* remove UPGRADE BLOCKER for hiredis

it was also addressed as a part of this PR

awx/main/wsrelay.py

@@ -8,7 +8,7 @@ import ipaddress
 
 import aiohttp
 from aiohttp import client_exceptions
-import aioredis
+import redis
 
 from channels.layers import get_channel_layer
 
@@ -199,7 +199,7 @@ class WebsocketRelayConnection:
                         return
 
                     continue
-                except aioredis.errors.ConnectionClosedError:
+                except redis.exceptions.ConnectionError:
                     logger.info(f"Producer {name} lost connection to Redis, shutting down.")
                     return