The nightly pinning is used by a bunch of different tools outside of
github actions, move the config file to the crate root.
Update the path in the justfile.
Done in preparation for fixing the git pre-commit hook.
If our custom dev scripts get a `just` command it makes them more
discoverable for new contributors.
Add a command to run the `update-lock-files.sh` script.
Tobin C. Harding