Ignore lockfile about cargo-outdated

[hougesen]

Just to clarify, what I am looking for/to do, is to check if the version in Cargo.toml is the latest.

Since the default for cargo add is to allow bumping the patch version of packages, it is pretty easy for Cargo.toml dependency versions to be out of sync with Cargo.lock. Especially if Cargo.lock is git ignored (See rust-lang/cargo/#315).

For most crates bumping the patch version does not matter much, but there are some libraries in Rust that have "alternative" versioning systems, like serde that has been bumping the patch version of v1.0.1 to v1.0.203 over the last 7 years.

That means the following Cargo.toml will result in 7 years of updates if the user is not careful.

# Cargo.toml

[package]
name = "dummy"
version = "0.1.0"
edition = "2021"

[dependencies]
serde = { version = "1.0.1" }

# Cargo.lock

[[package]]
name = "dummy"
version = "0.1.0"
dependencies = ["serde"]

[[package]]
name = "serde"
version = "1.0.203"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "7253ab4de971e72fb7be983802300c30b5a7f0c2e56fab8abfc6a214307c0094"
dependencies = ["serde_derive"]

# ...