Change 'zrange' args type hints - adding Optional type hint for args that can be None

[kesha1225]

Title:
fix(redis-client): change zrange num parameter type to Optional[int]

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Pull Request check‑list

• Do tests and lints pass with this change?
• Do the CI tests pass with this change (enable it first in your forked repo and wait for the GitHub Action build to finish)? (https://github.com/kesha1225/redis-py/actions/runs/14544583494)
• Is the new or changed code fully tested?
• Is a documentation update included (if this change modifies existing APIs, or introduces new ones)?
• Is there an example added to the examples folder (if applicable)?
• Was the change added to the CHANGES file?

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Description of change

This PR adjusts the signature of the zrange method in redis/commands/core.py, changing the num parameter from a plain int = None to Optional[int] = None.

• Motivation: align the type annotation with its optional usage and eliminate type‑checking errors.
• Behavior: no functional change—existing behavior remains identical.
• Tests & Docs: all existing unit tests and lint checks have been verified to pass; the docstring signature has been updated accordingly.

[petyaslavova]

You have several places where Union[int, None] is replaced with Optional[None]. Please check them and change to Optional[int]

[kesha1225]

fingers crossed this one gets merged after the latest update

[petyaslavova]

Just one more changes and it is done :)

[petyaslavova]

atr --> str