ci: allow dirty working tree for cargo publish

[tbille]

Summary

• Adds --allow-dirty flag to cargo publish in the release workflow

Why

The "Set version from tag" step modifies Cargo.toml in-place (via sed) without committing the change. By default cargo publish rejects uncommitted changes, causing the workflow to fail with:

error: 1 files in the working directory contain changes that were not yet committed into git:
Cargo.toml

The --allow-dirty flag is the correct fix here since the modification is intentional — the tag is the source of truth for the version.