bpo-46417: _PyStructSequence_FiniType() updates _Py_RefTotal (GH-30988)

Author: vstinner

Objects/structseq.c

@@ -553,6 +553,9 @@ _PyStructSequence_FiniType(PyTypeObject *type)
     // Undo Py_INCREF(type) of _PyStructSequence_InitType().
     // Don't use Py_DECREF(): static type must not be deallocated
     Py_SET_REFCNT(type, 0);
+#ifdef Py_REF_DEBUG
+    _Py_RefTotal--;
+#endif
 
     // Make sure that _PyStructSequence_InitType() will initialize
     // the type again