Checks are missing in release builds

On the current master, building ghostflow-director using the release profile (cargo build --release) results in a failure of the test test_checks_exist with error "the allow_robot check should be supported". This is also seen trying to run ghostflow-director to validate otherwise valid YAML config files with the checks: argument set at any level and with any of the available checks.

I'm not a Rust expert, but digging through things, this looks almost certainly related to: https://github.com/dtolnay/inventory/issues/32. Trying a very dumb binary project with

# Cargo.toml
[package]
name = "check-git-checks"
version = "0.1.0"
edition = "2021"

[dependencies]
inventory = "~0.1"
git-checks-config = "~0.1"
git-checks-core = "^1.0"
git-checks = { version = "^4.0", features = ["config"] }

and

// main.rs
use git_checks_config::{BranchCheckConfig, CommitCheckConfig, TopicCheckConfig};
use git_checks;
use inventory;

fn main() {
    println!("Hello, world!");

    for check in inventory::iter::<BranchCheckConfig> {
        println!("Found BranchCheck: {}", check.name());
    }
    for check in inventory::iter::<CommitCheckConfig> {
        println!("Found CommitCheck: {}", check.name());
    }
    for check in inventory::iter::<TopicCheckConfig> {
        println!("Found TopicCheck: {}", check.name());
    }
}

Results in output:

$ cargo run
Hello, world!
... all checks printed ...
Found TopicCheck: bad_commit/topic
$

and

$ cargo run --release
Hello, world!
$

I've tried out the suggested incremental and codegen-units changes with RUSTFLAGS in the inventory linked issue, but at least for the above example, these don't seem to change things (but I could well be doing something wrong here).

What does seem to fix things is pulling in one single thing from the git_checks crate:

// main.rs
use git_checks_config::{BranchCheckConfig, CommitCheckConfig, TopicCheckConfig};
use git_checks::AllowRobot;
use inventory;

fn main() {
    println!("Hello, world!");

    let _x = AllowRobot::builder();

    for check in inventory::iter::<BranchCheckConfig> {
        println!("Found BranchCheck: {}", check.name());
    }
    for check in inventory::iter::<CommitCheckConfig> {
        println!("Found CommitCheck: {}", check.name());
    }
    for check in inventory::iter::<TopicCheckConfig> {
        println!("Found TopicCheck: {}", check.name());
    }
}

which (with no other changes) results in:

$ cargo run --release
Hello, world!
... all checks printed ...
Found TopicCheck: bad_commit/topic
$

This isn't super-critical, but I've until now been doing our deployment of ghostflow-director in Docker/OpenShift using release builds for size/speed. I suspect using Debug builds for now will be o.k., but would be nice to have a working Release option.

I'm not enough of an Rust expert to suggest the best fix for this. Perhaps if something from git_checks needs to be pulled in, it could provide a function get_checks or similar? That could be used in ghostflow-director both in test_checks_exist to dynamically get the "standard" checks, maybe also to help with documenting checks and their allowed config?

Would be happy to prepare a MR for review on that if, or for other suggestions!