ignore: - dependency-name: DOES NOT WORK ?

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Package ecosystem

nuget (.NET)

### Manifest location and content before the Dependabot update

https://github.com/goswinr/Rhino.Scripting.FSharp/blob/53a9ca2e48ce1c2a76646e9a525925d4a15dcd09/Rhino.Scripting.Fsharp.fsproj#L65

### dependabot.yml content

https://github.com/goswinr/Rhino.Scripting.FSharp/blob/53a9ca2e48ce1c2a76646e9a525925d4a15dcd09/.github/dependabot.yml

### What you expected to see, versus what you actually saw

I have
``` yml
ignore:
- dependency-name: "RhinoCommon"
```
in dependabot.yaml

And still a PR for it was created:
See https://github.com/goswinr/Rhino.Scripting.FSharp/commit/27c1e3f21cf0a79531f5bb7abbb86d82a4aff217#diff-9f7fa7c73f96f9961c72d512993f2daafc09a4d62813156822701dfda35fca64L65

Did I miss the proper way [to ignore](https://docs.github.com/en/code-security/dependabot/working-with-dependabot/dependabot-options-reference#ignore--) some packages ?