ci(build): run cargo check on MSRV

[overlookmotel]

Run cargo check in CI on our MSRV. This should avoid problems like #8913.

[overlookmotel]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• ci(build): run cargo check on MSRV #8932 👈 (View in Graphite)
• chore(build): bump MSRV to 1.81.0 #8931
• style(all): replace #[allow] with #[expect] #8930
• main

---

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

• 0-merge - adds this PR to the back of the merge queue
• hotfix - for urgent hot fixes, skip the queue and merge this PR next

You must have a Graphite account in order to use the merge queue. Sign up using this link.

An organization admin has enabled the Graphite Merge Queue in this repository.

Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.

This stack of pull requests is managed by Graphite. Learn more about stacking.

[overlookmotel]

It doesn't work. It should be failing, because #8929 hasn't been merged yet. On my local machine, cargo ck fails on Rust 1.81.0 on this branch.

Any idea @Boshen? Or shall we just forget about it?