bump alloy to 0.12

[tbro]

Bumps alloy version to 0.12. We should benefit from some of the testing utilities. Though I'm unsure what else has changed since 0.9.

[github-actions]

Unable to build without Cargo.lock file.

This means that after this change 3rd party projects may have
difficulties using crates in this repo as a dependency. If this
isn't easy to fix please open an issue so we can fix it later.

For the first failing build see: https://github.com/EspressoSystems/espresso-network/actions/runs/13773607468

To reproduce locally run

cargo generate-lockfile
cargo check --all-targets

This PR can still be merged.