CI: Kani verifier v0.55.0 appears to have run out of memory

[tatsuya6502]

https://github.com/moka-rs/moka/actions/runs/10859450764/job/30138812482

cd .;
  cargo-kani --features 'sync, future'
  shell: /usr/bin/bash --noprofile --norc -e -o pipefail {0}
  env:
    CARGO_HOME: /home/runner/.cargo
    CARGO_INCREMENTAL: 0
    CARGO_TERM_COLOR: always
Kani Rust Verifier 0.55.0 (cargo plugin)
...

CBMC failed with status 137
VERIFICATION:- FAILED
CBMC appears to have run out of memory. You may want to rerun your proof in an environment with additional memory or use stubbing to reduce the size of the code the verifier reasons about.

Kani v0.54.0 was ok. So we will pin it to v0.54.0 for now.

[tatsuya6502]

Kani v0.54.0 was ok. So we will pin it to v0.54.0 for now.

Pinned it to v0.54.0 via #458.