All bookrunner examples show verification failures

Last week we noticed `bookrunner` failures had grown significantly after #738. We immediately shipped #868 to prevent this from happening again.

Upon closer inspection, it appears that all verification jobs are failing for this reason:
```bash
/home/runner/work/kani/kani/scripts/kani: line 21: /home/runner/work/kani/kani/target/*/cargo-kani: No such file or directory
```