Fix C++17 error: standard attributes in middle of decl-specifiers (CY…

…THON_UNUSED) (GH-5791)

This is only relevant on Python 3.13+

Fixes #5790

Cython/Utility/FunctionArguments.c

@@ -505,7 +505,7 @@ static int __Pyx_MergeKeywords(PyObject *kwdict, PyObject *source_mapping) {
     #define __Pyx_KwValues_FASTCALL(args, nargs) ((args) + (nargs))
     static CYTHON_INLINE PyObject * __Pyx_GetKwValue_FASTCALL(PyObject *kwnames, PyObject *const *kwvalues, PyObject *s);
 #if CYTHON_COMPILING_IN_CPYTHON && PY_VERSION_HEX >= 0x030d0000
-    static CYTHON_UNUSED PyObject *__Pyx_KwargsAsDict_FASTCALL(PyObject *kwnames, PyObject *const *kwvalues);/*proto*/
+    CYTHON_UNUSED static PyObject *__Pyx_KwargsAsDict_FASTCALL(PyObject *kwnames, PyObject *const *kwvalues);/*proto*/
   #else
     #define __Pyx_KwargsAsDict_FASTCALL(kw, kwvalues) _PyStack_AsDict(kwvalues, kw)
   #endif
@@ -563,7 +563,7 @@ static CYTHON_INLINE PyObject * __Pyx_GetKwValue_FASTCALL(PyObject *kwnames, PyO
 }
 
 #if CYTHON_COMPILING_IN_CPYTHON && PY_VERSION_HEX >= 0x030d0000
-static CYTHON_UNUSED PyObject *__Pyx_KwargsAsDict_FASTCALL(PyObject *kwnames, PyObject *const *kwvalues) {
+CYTHON_UNUSED static PyObject *__Pyx_KwargsAsDict_FASTCALL(PyObject *kwnames, PyObject *const *kwvalues) {
     Py_ssize_t i, nkwargs = PyTuple_GET_SIZE(kwnames);
     PyObject *dict;