Change StrictRedis usage to Redis

The StrictRedis class is only an alias for
Redis in >= 3.0.0

Change-Id: I89146dcf63cf984410f29b31ac2492f5ccaf3468

releasenotes/notes/remove-strict-redis-555f0f4e369480e3.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    The minimum redis-py version required is now >= 3.0.0

tooz/drivers/redis.py

@@ -454,10 +454,10 @@ return 1
             if 'sentinel_fallback' in kwargs:
                 del kwargs['sentinel_fallback']
             master_client = sentinel_server.master_for(sentinel_name, **kwargs)
-            # The master_client is a redis.StrictRedis using a
+            # The master_client is a redis.Redis using a
             # Sentinel managed connection pool.
             return master_client
-        return redis.StrictRedis(**kwargs)
+        return redis.Redis(**kwargs)
 
     @_handle_failures()
     def _start(self):