chore(deps): refresh dependencies

[daisuke8000]

Summary

• Refresh the pending Cargo and GitHub Actions dependency updates in one lockfile change.
• Upgrade crossbeam-epoch to 0.9.20 to address the RustSec advisory.
• Remove the obsolete CodeRabbit repository configuration and review-instruction files.

Verification

• cargo fmt --all --check
• cargo audit
• cargo build --workspace --locked
• cargo test --workspace
• cargo clippy --all-targets -- -D warnings

[daisuke8000]

@coderabbitai review