[3.12] gh-108267: Dataclasses docs: Fix object.__setattr__ typo (GH-108355) (#108358)

gh-108267: Dataclasses docs: Fix object.__setattr__ typo (GH-108355)

Fixed a sentence in dataclasses.rst

Changed "__setattr__" to "object.__setattr__" in a section that was specifically supposed to refer to the __setattr__ method of the object class. Also suppressed the link to the data model docs for __setattr__, since we're talking about a specific __setattr__ implementation, not __setattr__ methods in general.
(cherry picked from commit 79fdacc0059a3959074d2d9d054653eae1dcfe06)

Co-authored-by: FrozenBob <30644137+FrozenBob@users.noreply.github.com>