chore: fix pr check issues

[reubenmiller]

Fix various issues with current Rust pipeline. The different changes are still split in different commits, however all of the commits related to making the PR checks pass again (which should make it also easier to merge the PR without having to bypass any checks).

Fix clippy error on Rust stable.

error: useless conversion to the same type: `char`
  --> src/stress.rs:61:20
   |
61 |            .take(size)
   |   ____________________^
   |  |____________________|
62 | ||         .map(char::from)
   | ||________________________^
63 | |          .collect()
   | |_________- help: consider removing
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#useless_conversion
   = note: `-D clippy::useless-conversion` implied by `-D clippy::all`
   = help: to override `-D clippy::all` add `#[allow(clippy::useless_conversion)]`

Update spiffe dependency

The spiffe dependency was outdated and causing an error in the cargo-deny.

cargo-deny

cargo-deny has gone through some changes and many of the properties have been deprecated. Comments were removed from the deny.toml as the comments were introducing too much noise which made the file harder to read (imho). Two new advisories were added to the ignore list (with reasons) as one was due to the old clap version (due to current MSRV), and one due to using the unmaintained derivation crate. The latter will require a decision before a replacement can be applied to all related parsec projects.

[hug-dev]

Thanks a lot for your fixes here and in other repos!

[reubenmiller]

@hug-dev I've extended the scope of this PR to also include some of the additional changes to allow the PR checks to be able to pass. There were multiple issues which were blocking this (cargo-deny config, out of date libraries which caused cargo-deny to fail, clippy errors).

Once this is merged, then the PRs should be a lot slimmer.