[3.10] gh-93738: Documentation C syntax (:c:type:`PyTupleObject*` -> :c:expr:`PyTupleObject*`) (GH-97780) (#97864)

:c:type:`PyTupleObject*` -> :c:expr:`PyTupleObject*`
(cherry picked from commit 510baa429affb832d7b4ed68182e59daa2815d2e)

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>