Dependabot does not consider ignore rule

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Package ecosystem

nuget

### Package manager version

_No response_

### Language version

netstandard2.0

### Manifest location and content before the Dependabot update

https://github.com/jscarle/AttributeSourceGenerator/blob/main/src/AttributeSourceGenerator/AttributeSourceGenerator.csproj
```xml




```

### dependabot.yml content

https://github.com/jscarle/AttributeSourceGenerator/blob/main/.github/dependabot.yml
```yml
version: 2
updates:
- package-ecosystem: "nuget"
directory: "/"
schedule:
interval: "weekly"
ignore:
- dependency-name: "Microsoft.CodeAnalysis.CSharp"
```

### Updated dependency

Microsoft.CodeAnalysis.CSharp 4.3.1 => 4.9.2

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

Ignore should be respected and PR should not be opened.

### Native package manager behavior

_No response_

### Images of the diff or a link to the PR, issue, or logs

https://github.com/jscarle/AttributeSourceGenerator/pull/4

### Smallest manifest that reproduces the issue

```yml
version: 2
updates:
- package-ecosystem: "nuget"
ignore:
- dependency-name: "Microsoft.CodeAnalysis.CSharp"
```

Start by comparing the ignore rule in .github/dependabot.yml with the Microsoft.CodeAnalysis.CSharp reference in AttributeSourceGenerator.csproj and the update shown in pull request #4. Reproduce the smallest manifest case, then trace the NuGet update handling; done means the ignore rule prevents a pull request from being opened.

Written by the indexing model from the issue text.