bpo-45439: Rename _PyObject_CallNoArg() to _PyObject_CallNoArgs() (GH-28891)

Fix typo in the private _PyObject_CallNoArg() function name: rename
it to _PyObject_CallNoArgs() to be consistent with the public
function PyObject_CallNoArgs().

Objects/iterobject.c

@@ -217,7 +217,7 @@ calliter_iternext(calliterobject *it)
         return NULL;
     }
 
-    result = _PyObject_CallNoArg(it->it_callable);
+    result = _PyObject_CallNoArgs(it->it_callable);
     if (result != NULL) {
         int ok;