[3.12] gh-131885: Document that `dict.setdefault` and `dict.get` take no keyword arguments (GH-128208) (#131894)

gh-131885: Document that `dict.setdefault` and `dict.get` take no keyword arguments (GH-128208)
(cherry picked from commit edfbd8c062285e83dc5f596288df2a762e68bcdc)

Co-authored-by: Adam Dangoor <adamdangoor@gmail.com>