When our code calls register_script on a RedisCluster script, mypy flags the call as an error because the register_script method is defined like this in ScriptComamnds:

    def register_script(self: "redis.client.Redis", script: ScriptTextT) -> Script:
        # ... lines omitted ...
        return Script(self, script)

I believe this was done because the Script class expects an object of type redis.client.Redis, but I'd imagine this could be solved by making Script accept Union[Redis, RedisCluster] instead.

Steps to Repro

1. Create a file with these contents:

   from typing import Union
   
   import redis
   from redis.commands.core import Script
   
   
   def load_script(redis_connection: Union[redis.Redis, redis.RedisCluster], script_filename: str) -> Script:
       with open(script_filename) as lua_script_file:
           lua_script_contents = lua_script_file.read()
   
           return redis_connection.register_script(lua_script_contents)

2. Run mypy on the code.

Expected Results

No error from mypy.

Actual Results

mypy prints this error:

example.py:11: Invalid self argument "RedisCluster" to attribute function "register_script" with type "Callable[[Redis, Union[bytes, str, memoryview[int]]], Script]