bpo-37483: add _PyObject_CallOneArg() function (#14558)

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 0cc1443..422f4b0 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -2113,8 +2113,7 @@
             _Py_IDENTIFIER(__missing__);
             missing = _PyObject_LookupSpecial((PyObject *)mp, &PyId___missing__);
             if (missing != NULL) {
-                res = PyObject_CallFunctionObjArgs(missing,
-                                                   key, NULL);
+                res = _PyObject_CallOneArg(missing, key);
                 Py_DECREF(missing);
                 return res;
             }