gh-77560: Report possible errors in restoring builtins at finalization (GH-94255)

Seems in the past the copy of builtins was not made in some scenarios,
and the error was silenced. Write it now to stderr, so we have a chance
to see it.

Python/pylifecycle.c

@@ -1462,7 +1462,7 @@ finalize_restore_builtins(PyThreadState *tstate)
     }
     PyDict_Clear(interp->builtins);
     if (PyDict_Update(interp->builtins, interp->builtins_copy)) {
-        _PyErr_Clear(tstate);
+        PyErr_WriteUnraisable(NULL);
     }
     Py_XDECREF(dict);
 }