pythongh-93738: Documentation C syntax (:c:type:Py_UNICODE* -> :c:expr:Py_UNICODE*) (pythonGH-97784)

:c:type:`Py_UNICODE*` -> :c:expr:`Py_UNICODE*`
(cherry picked from commit a081cae)

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

Author: AA-Turner

Doc/whatsnew/3.3.rst

@@ -2267,7 +2267,7 @@ The :c:type:`Py_UNICODE` has been deprecated by :pep:`393` and will be
 removed in Python 4. All functions using this type are deprecated:
 
 Unicode functions and methods using :c:type:`Py_UNICODE` and
-:c:type:`Py_UNICODE*` types:
+:c:expr:`Py_UNICODE*` types:
 
 * :c:macro:`PyUnicode_FromUnicode`: use :c:func:`PyUnicode_FromWideChar` or
   :c:func:`PyUnicode_FromKindAndData`