plugin cargo-workspace missing some file update

#### Environment details

- OS: Ubuntu 24.04.2
- Node.js version: 20.19.0
- npm version: 10.8.2
- `release-please` version: 16.18.0

> GitHub action with `googleapis/release-please-action@v4`

#### Steps to reproduce

1. create a cargo workspace
2. make this repo as one version `{".": x.y.z}` in `.release-please-manifest.json`

The plugin cargo-workspace seems will skip `cargo.lock` update (missing members version update) and `.github/.release-please-manifest.json`

```
# manifest.json
...
"plugins": ["cargo-workspace"],
...
```
If you add "plugins": ["cargo-workspace"], to the config.json , release-please will skip the Cargo.lock's member updates and manifest.json's version updates.

you can see entire repo construct in https://github.com/toyfield/cargo-workspace-release-please