Fix verify-std-check outcome check

[celinval]

It looks like I used output instead of outcome variable.

I noticed that this PR should've failed the workflow but it didn't because of this mistake.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.

[jaisnan]

Oops, should have caught this in my review. in any case, thanks!

Can we add a comment somewhere that all toolchain upgrade failures that are resolved manually should trigger a failure for this CI check?

[celinval]

We currently have the following blob at the top of the workflow file:

# We expect toolchain updates to potentially break this workflow in cases where
# the version tracked in the `verify-rust-std` is not compatible with newer
# versions of the Rust toolchain.
#
# Changes unrelated to the toolchain should match the current status of main.

Do you have anything else in mind?

[jaisnan]

We currently have the following blob at the top of the workflow file:

# We expect toolchain updates to potentially break this workflow in cases where
# the version tracked in the `verify-rust-std` is not compatible with newer
# versions of the Rust toolchain.
#
# Changes unrelated to the toolchain should match the current status of main.

Do you have anything else in mind?

Just maybe a small clarification like ->

# We expect toolchain updates to potentially break this workflow in cases where
# the version tracked in the `verify-rust-std` is not compatible with newer 
# versions of the Rust toolchain. 
# For example, toolchain upgrade breaks such as 
# https://github.com/model-checking/kani/issues/3369.
#
# Changes unrelated to the toolchain should match the current status of main.

It's okay if this change is not added, this is purely for me because i like examples in comments.

[celinval]

I agree that an example can be very helpful, but I'm not sure the PR you mentioned is a good reference. Maybe we can add a better link later.

The PR didn't actually fail the workflow, and the workflow logs themselves won't be available for more than a few days. So it might be confusing to use this as a reference.