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().

Python/codecs.c

@@ -280,7 +280,7 @@ PyObject *codec_makeincrementalcodec(PyObject *codec_info,
     if (errors)
         ret = PyObject_CallFunction(inccodec, "s", errors);
     else
-        ret = _PyObject_CallNoArg(inccodec);
+        ret = _PyObject_CallNoArgs(inccodec);
     Py_DECREF(inccodec);
     return ret;
 }