Decode responses from redis

FIxes:

    return_value = f(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/flanker/addresslib/address.py", line 322, in validate_address
    plugin = plugin_for_esp(exchanger)
  File "/usr/local/lib/python3.8/site-packages/flanker/addresslib/validate.py", line 129, in plugin_for_esp
    if grammar[0].match(mail_exchanger):
TypeError: cannot use a string pattern on a bytes-like object

flanker/addresslib/drivers/redis_driver.py

@@ -15,7 +15,7 @@ def __init__(self, host=None, port=None, prefix='mxr:', ttl=604800):
         host = host or os.environ.get('REDIS_HOST', 'localhost')
         port = port or os.environ.get('REDIS_PORT', 6379)
         db = os.environ.get('REDIS_DB', 0)
-        self.r = redis.StrictRedis(host=host, port=port, db=db)
+        self.r = redis.StrictRedis(host=host, port=port, db=db, decode_responses=True)
 
     def __getitem__(self, key):
         try: