Wrongly closing PRs as "dependency no longer updateable", when nothing has changed since the last run

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Package ecosystem

cargo

### Package manager version

_No response_

### Language version

_No response_

### Manifest location and content before the Dependabot update

_No response_

### dependabot.yml content

_No response_

### Updated dependency

_No response_

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

https://github.com/ruffle-rs/ruffle/pull/17567#issuecomment-2297369877 and https://github.com/ruffle-rs/ruffle/pull/16835#issuecomment-2297369714 were closed, when they shouldn't have been.

### Native package manager behavior

_No response_

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

_No response_

### Smallest manifest that reproduces the issue

_No response_

Start with the two referenced Ruffle pull requests and their linked comments, then trace the Dependabot run that classified them as “dependency no longer updateable.” Confirm the behavior with a Cargo update case where nothing changed; done means unchanged dependencies are not incorrectly closed for that reason.

Written by the indexing model from the issue text.