test(evm-core): fix stale delegation.rs test module

[manuelmauro]

Problem

evm-core's core/src/delegation.rs has a #[cfg(test)] mod tests that does not compile:

• Delegation::try_from(&bytes) is called with bytes: Vec<u8> (so the argument is &Vec<u8>), but the impl is TryFrom<&[u8]> — trait selection does not deref-coerce &Vec<u8> to &[u8].
• The assertions compare against Some(..) / None, but try_from returns Result<Delegation, DelegationError>.

The module has been broken since #367 first added the file — the test was written against an Option-returning draft of the Delegation API, while the merged impl returns Result via TryFrom.

Why CI didn't catch it

The root Cargo.toml is both a [package] (evm) and a [workspace], with no default-members. Per Cargo's rules, commands run from the root then default to the root package only — so cargo test (the workflow's only test step) never descends into evm-core, and cargo build compiles evm-core only as a dependency (a dependency's #[cfg(test)] modules are never built). cargo clippy --all lints lib/bin targets but not test targets.

It surfaces with:

cargo check --workspace --tests

Fix

• Pass a &[u8] (bytes.as_slice()) so the TryFrom<&[u8]> impl is selected.
• Compare against Ok(..) / Err(DelegationError::InvalidFormat).

Test-only change; no library code is touched.

Optional follow-up

Adding --workspace to the cargo test step in .github/workflows/rust.yml would catch this whole class of never-compiled test code across core/gasometer/runtime/fuzzer.