Filter extra deps on keccak on macOS that fails snap testing

[mamcx]

Description of Changes

This is a workaround to make it possible to run cargo test --all.

Only on macOS when running the cargo insta on the deptree_snapshot test it gets an extra deps of

sha3 v0.10.8
└── keccak v0.1.4
            └── cpufeatures v0.2.9 # Extra on macOS
                        └── libc v0.2.153

... that causes all the other test fails by PoisonError.

Expected complexity level and risk

1

Testing

Describe any testing you've done, and any testing you'd like your reviewers to do, so that you're confident that all the changes work as expected!

• [x] Confirm with joshua this happens on macOS
• [x] Check cargo test --all now can run.