fix: forward kwargs to aioredis in Redis backends

[dimitryLMEX]

Summary

RedisCallback.__init__ accepted **kwargs but never stored or forwarded them to aioredis.from_url(). Any keyword argument passed at construction time (e.g. password, ssl, decode_responses) was silently discarded, making password-protected Redis instances unusable.

Fix

Store the extra kwargs in self.conn_kwargs and unpack them into every aioredis.from_url() call across the three writer classes.

# RedisCallback.__init__  (new line)
self.conn_kwargs = kwargs

# Each writer()  (before → after)
conn = aioredis.from_url(self.redis)
conn = aioredis.from_url(self.redis, **self.conn_kwargs)

Fixes #1032