doesn't genereate new release

I am trying to draft a new release using

```
gren release --tags=v3.0.6..3.0.7
```
The following tag is not found in the repository: 3.0.7. please provide existing tags.

Start by reproducing the `gren release --tags=v3.0.6..3.0.7` command in the github-tools/github-release-notes repository and inspect how the `gren release` entry point resolves tag ranges. Confirm the expected behavior for the reported missing `3.0.7` tag and document or test the supported tag syntax.

索引モデルが issue の本文から書いたものです。