Add upgrade reminder

### Pre-flight checklist

- [X] I have read the [contribution documentation](https://github.com/electron/forge/blob/main/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [code of conduct](https://github.com/electron/electron/blob/main/CODE_OF_CONDUCT.md) that this project uses.
- [X] I have searched the issue tracker for a feature request that matches the one I want to file, without success.

### Problem description

Forge users should stay up-to-date with the latest version as much as possible. We currently don't have a way of alerting people to bump their packages up.

### Proposed solution

Docusaurus prints out this little message when you run a production build. Something similar for Forge would be nice.

```

╭─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ │
│ Update available 2.0.1 → 2.2.0 │
│ │
│ To upgrade Docusaurus packages with the latest version, run the following command: │
│ `yarn upgrade @docusaurus/core@latest @docusaurus/plugin-google-analytics@latest @docusaurus/plugin-ideal-image@latest @docusaurus/preset-classic@latest │
│ @docusaurus/remark-plugin-npm2yarn@latest @docusaurus/types@latest` │
│ │
╰─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯
```

### Alternatives considered

Not showing a message.

### Additional information

_No response_