* CI: update to checkout@v4 action
Not sure why they decided to bump a major version. It seems like this is
unnecessary churn: https://github.com/actions/checkout/pull/1436#issuecomment-1737711301
* CI: replace archived `actions-rs/toolchain`
It's been unmaintained for four years and has been throwing warnings in
CI:
> The `set-output` command is deprecated and will be disabled soon.
* CI: Bump `cargo-install` action.
This should fix the remaining warnings in CI?
* CI: mdbook-linkcheck: workaround for build error
* speed up cargo check
* fix
* composite
* plural
* wrong name
* go brrrrrrrr
* bash
* aaaaa
* why not even more?
* more composite
* fix
* miri
* test for llvm >= 16
* v2
* v2
* naaaa
* JUST MORE INSTANCES
* aa
* fix
* no bash for windows
* reduce a bit as some guys are delayed
* no deps
