Validate the versions in our Cargo.toml file

[coryan]

We have a customer using a rather old version of Tokio. They can upgrade but need a recommendation. Our Cargo.toml file says >= 1.0, but the .lock file uses 1.45 (as I write this). We could say "use 1.45", but the more interesting question is "what do we tell each new customer that asks similar questions?".

We need a mechanism to validate the versions in our Cargo.toml file, and where they are "too loose", we need to tighten them so they reflect our real requirements.

[coryan]

This was fixed in #3008