Execution model reference should cover `closure` arg to `exec` & `eval`

When the closure parameter was added to exec and eval for Python 3.11, it rendered the "Interaction with dynamic features" part of the execution model reference slightly out of date: https://docs.python.org/3/reference/executionmodel.html#interaction-with-dynamic-features

The text remains accurate for string execution, but needs updating to correctly cover execution of code objects with closure variable references.

Linked PRs

• gh-155014

從 issue 中連結的執行模型參考文件的「Interaction with dynamic features」區段開始，並查看連結的 PR gh-155014 以了解現有工作。更新該參考文件，使其對字串執行仍然正確，同時也涵蓋透過 exec 和 eval 傳遞的、包含閉包變數參照的程式碼物件。