[3.12] Correct description of inheriting from another class (GH-114660) (#114868)

"inherits <someclass>" grates to this reader. I think it should be "inherits from <someclass>".
(cherry picked from commit c9c6e04380ffedd25ea2e582f9057ab9612960c9)

Co-authored-by: Skip Montanaro <skip.montanaro@gmail.com>