Getting git_dependencies_not_reachable

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Package ecosystem

GitHub Actions

### Package manager version

_No response_

### Language version

_No response_

### Manifest location and content before the Dependabot update

_No response_

### dependabot.yml content

version: 2

registries:
github-rba:
type: git
url: https://github.com
username: x-access-token
password: ${{ secrets.RBA_REPO_TOKEN }}

updates:
- package-ecosystem: github-actions
registries: "*"
directory: /
groups:
github-actions:
patterns:
- "*"
update-types:
- minor
- patch
commit-message:
prefix: deps
labels:
- kind/dependencies
schedule:
interval: weekly

### Updated dependency

_No response_

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

I'd expect Dependabot to be able to check for both public and private dependencies as it has been doing (this was working last week), but instead Dependabot fails with a 401 for public dependencies as these can't be accessed with the token.

> Dependabot encountered '6' error(s) during execution, please check the logs for more details.
+---------------------------------------------------------------------------------------------------------------------------------------------------------+
| Dependencies failed to update |
+-----------------------------------------------+--------------------------------+------------------------------------------------------------------------+
| Dependency | Error Type | Error Details |
+-----------------------------------------------+--------------------------------+------------------------------------------------------------------------+
| action-stars/install-tool-from-github-release | git_dependencies_not_reachable | { |
| | | "dependency-urls": [ |
| | | "https://github.com/action-stars/install-tool-from-github-release" |
| | | ] |
| | | } |
| actions/checkout | git_dependencies_not_reachable | { |
| | | "dependency-urls": [ |
| | | "https://github.com/actions/checkout" |
| | | ] |
| | | } |
| actions/upload-artifact | git_dependencies_not_reachable | { |
| | | "dependency-urls": [ |
| | | "https://github.com/actions/upload-artifact" |
| | | ] |
| | | } |
| 8BitJonny/gh-get-current-pr | git_dependencies_not_reachable | { |
| | | "dependency-urls": [ |
| | | "https://github.com/8bitjonny/gh-get-current-pr" |
| | | ] |
| | | } |
| peter-evans/find-comment | git_dependencies_not_reachable | { |
| | | "dependency-urls": [ |
| | | "https://github.com/peter-evans/find-comment" |
| | | ] |
| | | } |
| actions/github-script | git_dependencies_not_reachable | { |
| | | "dependency-urls": [ |
| | | "https://github.com/actions/github-script" |
| | | ] |
| | | } |
+-----------------------------------------------+--------------------------------+------------------------------------------------------------------------+

### 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_