pythongh-93738: Documentation C syntax (:c:type:PyBytesObject* -> :c:expr:PyBytesObject*) (pythonGH-97782)

:c:type:`PyBytesObject*` -> :c:expr:`PyBytesObject*`
(cherry picked from commit 9ebc508)

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

Author: AA-Turner

Doc/c-api/unicode.rst

@@ -853,7 +853,7 @@ argument parsing, the ``"O&"`` converter should be used, passing
    ParseTuple converter: encode :class:`str` objects -- obtained directly or
    through the :class:`os.PathLike` interface -- to :class:`bytes` using
    :c:func:`PyUnicode_EncodeFSDefault`; :class:`bytes` objects are output as-is.
-   *result* must be a :c:type:`PyBytesObject*` which must be released when it is
+   *result* must be a :c:expr:`PyBytesObject*` which must be released when it is
    no longer used.
 
    .. versionadded:: 3.1