bpo-35459: Use PyDict_GetItemWithError() instead of PyDict_GetItem(). (GH-11112)

diff --git a/Include/cpython/dictobject.h b/Include/cpython/dictobject.h
index 4c7457c..64c012a 100644
--- a/Include/cpython/dictobject.h
+++ b/Include/cpython/dictobject.h
@@ -35,6 +35,7 @@
                                        Py_hash_t hash);
 PyAPI_FUNC(PyObject *) _PyDict_GetItemIdWithError(PyObject *dp,
                                                   struct _Py_Identifier *key);
+PyAPI_FUNC(PyObject *) _PyDict_GetItemStringWithError(PyObject *, const char *);
 PyAPI_FUNC(PyObject *) PyDict_SetDefault(
     PyObject *mp, PyObject *key, PyObject *defaultobj);
 PyAPI_FUNC(int) _PyDict_SetItem_KnownHash(PyObject *mp, PyObject *key,