Change Cargo.lock like -Z minimal-versions wants
We have combined
- Add a crate depending on our in-tree derive-deftly "0.11.0"
- Restore the compat tests, using crates.io derive-deftly 0.11.0
This seems to have reuslted in a Cargo.lock.minimal (from 1) which works, but which due to (2) cargo wants to change.