[docs] Specify that unittest.mock.patch.dict does not make a deepcopy

Documentation

I always assumed that unittest.mock.patch.dict made a recursive (deep) copy of the dict and restored it afterwards.
It turns out it is a "simple" copy()

We should maybe clarify that in the documentation

Example:

foo = {
  "bar": {"baz": 1}
}

with patch.dict(foo, {"unrelated": 123}):
  foo["bar"]["baz"] = 2

# baz will stay at 2, assumed it was reset to the original 1

Linked PRs

• gh-144434

從 unittest.mock.patch.dict 文件開始，檢查現有關於如何還原字典的說明。明確說明它使用的是淺層複製，而不是遞迴 deepcopy，並使用 issue 中的巢狀字典範例來展示內部變更仍會保留。編輯後檢查文件建置。