Update client.py sleep_time typing for run_in_thread function (#2977)

Changed from 
`sleep_time: int = 0`
to
`sleep_time: float = 0.0`
To avoid Pylance complaining: 
`Argument of type "float" cannot be assigned to parameter "sleep_time" of type "int" in function "run_in_thread"
  "float" is incompatible with "int"`

redis/client.py

@@ -1100,7 +1100,7 @@ def handle_message(self, response, ignore_subscribe_messages=False):
 
     def run_in_thread(
         self,
-        sleep_time: int = 0,
+        sleep_time: float = 0.0,
         daemon: bool = False,
         exception_handler: Optional[Callable] = None,
     ) -> "PubSubWorkerThread":