chore(python): fix incorrect import statement in README#604

parthea merged 1 commit intomaingoogleapis/python-datastore:mainfrom

owl-bot-update-lock-023a21377a2a00008057f99f0118edadc30a19d1636a3fee47189ebec2f3921cgoogleapis/python-datastore:owl-bot-update-lock-023a21377a2a00008057f99f0118edadc30a19d1636a3fee47189ebec2f3921cCopy head branch name to clipboard