pre ceremony house keeping

[flihp]

It's only been a few months since the last development push before a ceremony but things get out of date fast. This shouldn't be much work but we need to update dependencies, CI / infra stuff, and pin to a rust stable release that's compatible w/ the next release of OKOS: https://github.com/oxidecomputer/offline-keystore-os/issues/21

[flihp]

https://github.com/flihp/offline-keystore/tree/toolchain-upgrade
https://github.com/flihp/offline-keystore/tree/cargo-update

[flihp]

cargo update & toolchain update are done ... working through the dependency dashboard to roll stuff in Cargo.toml forward now