Changelog: document `Py_AtExit` requirement change that the interpreter must be initialized

Documentation

Python 3.12 has commit 2ad2bd8b14505ee92600e7988379cfac63086dab which now requires that the interpreter be initialized before calling Py_AtExit. Please add a retroactive note to the changelog for 3.12 and a new one to 3.13 (for those who don't go back to read the 3.12 changelogs) about this new change.

The API docs might also want to mention it too.

先閱讀提交 2ad2bd8b14505ee92600e7988379cfac63086dab，並找到 Python 3.12 和 3.13 的 changelog 區段。在兩個 changelog 中記錄：呼叫 Py_AtExit 前必須初始化直譯器；接著檢查 API 文件，以判斷是否也應在其中註明相同的要求。