Remove deprecated `PySys_ResetWarnOptions` C-API function

# Feature or enhancement

It was deprecated in https://github.com/python/cpython/pull/105179 / https://github.com/python/cpython/issues/105145

Now (in 3.15) it is time to remove it.

Since this is the only function from there in `sysmodule` - I prefer to delete them by module basis.

I have a PR ready.


### Linked PRs
* gh-138887