Update dependency versions in `Cargo.toml` to that of `Cargo.lock`

as per https://github.com/rust-lang/compiler-team/pull/89#issuecomment-494693064

what do you think about having https://github.com/rust-lang/rust/issues/57443 in `cargo edit`. Maybe as `cargo edit sync-with-lockfile`?

related: https://github.com/killercup/cargo-edit/issues/41

cc @polybuildr

Start by reading the request to update dependency versions in Cargo.toml from Cargo.lock, then review the linked compiler-team discussion, Rust issue 57443, and cargo-edit issue 41. Clarify whether the intended outcome is a cargo edit sync-with-lockfile command and define its behavior before implementation.

Written by the indexing model from the issue text.