Can I group the issues by specific label instead of the first label？

I got following error when group by specific label, can I do it by any option?
gren's version is 0.17.0
```
gren release --group-by "Type:Bug" --tags=v0.1.0..v0.2.0 --override

🤖 - Generate release notes:
===================================
✔ Releases found: 2
✔ Tags found: v0.2.0, v0.1.0
✔ Issues found: 63
The option for groupBy is invalid, please check the documentation

```

Start with the `gren release --group-by` command using the reported `Type:Bug` value and trace the `groupBy` option handling that produces the invalid-option message. Determine the supported grouping syntax and whether a specific label can be selected; done means the command works as requested or the limitation is clearly documented.

索引モデルが issue の本文から書いたものです。