incompatibility with latest client_info.py

If I don't comment out the row " d["mock"]..." below which was added in the latest release of exploration-tool-repo I will not be able to run the grass detection training ipynb-example.

    def _migrate_pre_v6_dict(d: dict[str, Any]) -> dict[str, Any]:
        ....
        d["mock"] = None if d.pop("mock") is None else {}