Unpin clap dependency

[jhpratt]

I'm unable to see why this was pinned in the first place. As pinning is unidiomatic and causes unexpected build failures, let's unpin it.

[waywardmonkeys]

If you look at the history for that line, you'll see this was done in #768 because of MSRV issues.

If you want to unpin this, then it would be better to add Cargo.lock (remove it from .gitignore as well) and have Cargo.lock use versions that are compatible with our MSRV.

[jhpratt]

I've done just that. Committing Cargo.lock is considered best practice in Rust nowadays regardless 🙂

[kaivol]

Are there any plans to merge this PR?

The current situation makes it impossible to use criterion in a cargo workspace where newer versions of clap are used.

[lemmih]

Need someone to review this PR.

[waywardmonkeys]

@lemmih This PR is fine as-is, and then we can do follow ups to potentially update the Cargo.lock some and perhaps evaluate what the current MSRV should be.

[waywardmonkeys]

(I didn't look at the actual current contents of the Cargo.lock and assumed it was valid.)

[jhpratt]

I assure you that the Cargo.lock was auto-generated at the time of opening the PR. I have no doubt that there are things out of date in it by now, however. It's trivial to regenerate it from scratch if preferred.