Export `throttle_script`

[dingxiong]

Hi,

Thanks for this convenient package! A tiny request. Could we export variable throttle_script inside throttle.py?

I plan to write unit tests using fakeredis. However fakeredis does not support redis.replicate_commands(). So I need a way to modify the lua script by myself.

E           redis.exceptions.ResponseError: Error running script (call to f_57d9369ec2fd631bd269fa0d567b1721077d04c0): @user_script:?: [string "<python>"]:10: attempt to call a nil value (field 'replicate_commands')
E           stack traceback:
E               [string "<python>"]:10: in main chunk

/opt/homebrew/Caskroom/miniforge/base/envs/website-py3_11_0/lib/python3.11/site-packages/fakeredis/_server.py:85: ResponseError