docs(python): Add 'frame_equal' renamed to 'equals' comment to v1 Upgrade Guide

[DeflateAwning]

Fixes #17998

[stinodego]

We do not include all renamings / things that were deprecated before. The list is simply too long. Check out the real changelog for an overview of those functions.

[DeflateAwning]

There is no deprecation warning on this though. Either Deprecation Warnings need to be set reliably, or they need to be included in the upgrade guide.

You make it very difficult to trust upgrading Polars.

Furthermore, @ritchie46 told me to create a PR. I'm now annoyed twice:

1. That I didn't know about the change before it started breaking things, despite reading every single word in the upgrade guide.
2. That I wasted my time creating a PR.

Why are you so afraid of the upgrade guide being long? It was a massive upgrade, with lots of breaking changes.

[stinodego]

There is no deprecation warning on this though.

There was a deprecation warning since 0.19.16, both when using the function and in the docstring.

Plus here's a full overview of scheduled removals, which is part of the release notes:
#16715

[DeflateAwning]

Fair enough; TIL my test workflow neglects DeprecationWarnings in unit tests :)