Also run the `rust` checks on "milestone" CLI releases, to ensure we
remain backward compatible with those versions. This was prompted by
https://github.com/github/codeql-action/pull/2960#pullrequestreview-3104730221
Running this on current `main` and then on that PR should improve our
confidence we remain backward compatible.
It also turns out a probable `ruamel.yaml` update was changing a lot of
generated workflows, so I've:
* fixed the `ruamel.yaml` version to the latest in `sync.sh`
* added `yaml.width = 120` in `sync.py` to minimize (but not entirely
remove) the number of changes
* checked in the workflows whose formatting was changed by the new
`ruamel.yaml` version
