[3.13] pythongh-119704: Fix reference leak in the ``Python/Python-tok…

…enize.c`` (pythonGH-119705) (python#119707)

Python/Python-tokenize.c

@@ -311,6 +311,7 @@ static void
 tokenizeriter_dealloc(tokenizeriterobject *it)
 {
     PyTypeObject *tp = Py_TYPE(it);
+    Py_XDECREF(it->last_line);
     _PyTokenizer_Free(it->tok);
     tp->tp_free(it);
     Py_DECREF(tp);