[3.13] GH-65961: Document the deprecation of `__package__` and `__cached__` (GH-124377) by miss-islington · Pull Request #124380 · python/cpython

…ed__` (pythonGH-124377)

The code changes for warning related to `__package__` landed in Python 3.12. `__cached__` doesn't have any changes as it isn't used but only set by the import system.
(cherry picked from commit 67201ad)

Co-authored-by: Brett Cannon <brett@python.org>

Because these attributes were *already* deprecated, the only change now is to document those previous deprecations.

Co-authored-by: T. Wouters <thomas@python.org>