Add suopport for unix-sock protocol (async redis)

src/socketio/async_redis_manager.py

@@ -70,7 +70,7 @@ class AsyncRedisManager(AsyncPubSubManager):  # pragma: no cover
     def _get_redis_module_and_error(self):
         parsed_url = urlparse(self.redis_url)
         schema = parsed_url.scheme.split('+', 1)[0].lower()
-        if schema == 'redis':
+        if schema in ['redis', 'unix']:
             if aioredis is None or RedisError is None:
                 raise RuntimeError('Redis package is not installed '
                                    '(Run "pip install redis" '