chore: test external push to protected branch

Pushing this commit to the `libevm` branch fails (by design) because of branch protection requiring a PR. I want to test what happens if, once the PR is approved and all status checks pass, I _locally_ `git merge --ff-only` on the `libevm` branch before pushing to GitHub. Will it recognise and honour the PR?

Without this, the GitHub PR merge uses `--no-ff`, which isn't always desirable.