gh-154757: Unschedule removal of Py_UNICODE (and Py_UNICODE_TYPE)

PEP-387 says (and did say back when these types were deprecated in 3.13):

> If the expected maintenance overhead and security risk of the
> deprecated behavior is small (e.g. an old function is
> reimplemented in terms of a new, more general one),
> it can stay indefinitely (or until the situation changes).

There's no need to remove these.

Author: encukou

Doc/c-api/unicode.rst

@@ -1865,17 +1865,18 @@ Deprecated API
 The following API is deprecated.
 
 .. c:type:: Py_UNICODE
+            Py_UNICODE_TYPE
 
-   This is a typedef of :c:type:`wchar_t`, which is a 16-bit type or 32-bit type
-   depending on the platform.
+   These are both typedefs of :c:type:`wchar_t`, which is a 16-bit type
+   or 32-bit type depending on the platform.
    Please use :c:type:`wchar_t` directly instead.
 
    .. versionchanged:: 3.3
       In previous versions, this was a 16-bit type or a 32-bit type depending on
       whether you selected a "narrow" or "wide" Unicode version of Python at
       build time.
 
-   .. deprecated-removed:: 3.13 3.16
+   .. deprecated:: 3.13
 
 
 .. c:function:: int PyUnicode_READY(PyObject *unicode)

Doc/deprecations/c-api-pending-removal-in-3.16.rst

@@ -83,5 +83,3 @@ Pending removal in Python 3.16
   The :c:func:`Py_InitializeFromConfig` API should be used with
   :c:type:`PyConfig` to set these options. Or :c:func:`PyConfig_Get` can be
   used to get these options at runtime.
-
-* :c:type:`Py_UNICODE` which was deprecated by :pep:`393`.

Doc/whatsnew/3.16.rst

@@ -1386,6 +1386,9 @@ Deprecated C APIs
   Use the safer :c:type:`PyUnicodeWriter` API instead.
   (Contributed by Victor Stinner in :gh:`157710`.)
 
+* :c:type:`Py_UNICODE` and :c:type:`Py_UNICODE_TYPE` are deprecated, but
+  no longer scheduled for removal.
+
 .. Add C API deprecations above alphabetically, not here at the end.
 
 .. include:: ../deprecations/c-api-pending-removal-in-3.18.rst