[3.12] GH- gh-111700: Fix syntax highlighting for C code in the "What's New In Python 3.12" documentation (GH-113609) (#113610)

GH- gh-111700: Fix syntax highlighting for C code in the "What's New In Python 3.12" documentation (GH-113609)

Fix PEP 684 syntax highlighting in what's new Python 3.12
(cherry picked from commit 9ce6c01e38a2fc7a5ce832f1f8c8d9097132556d)

Co-authored-by: Parth Doshi <doshi.parth9@gmail.com>