abc CLI can not get git credentials when running in an Actions workflow

### TL;DR

https://github.com/theteamatx/x-refinery-org/actions/runs/10708138099/job/29689738327?pr=1110

```
Run ./scripts/check-manifests.sh

abc version 0.10.0 is available at [https://github.com/abcxyz/abc]. Use ABC_IGNORE_VERSIONS="0.10.0" (or "all") to ignore.
when upgrading the manifest at /home/runner/work/x-refinery-org/x-refinery-org/.abc/manifest_github.com_abcxyz_packer-template_abc.templates_packer-project_2024-09-04T19:15:25.670581433Z.lock.yaml:
failed downloading template: Clone() of https://github.com/abcxyz/packer-template.git: exec of [git clone -- https://github.com/abcxyz/packer-template.git /tmp/git-clone-782347458] failed: error was "exit status 128", context error was "%!w()"\nstdout: \nstderr: Cloning into '/tmp/git-clone-782347458'...
fatal: could not read Username for 'https://github.com': No such device or address
```

### Expected behavior

_No response_

### Observed behavior

_No response_

### Environment Details

```markdown
To reproduce:

* Re-render/upgrade abc template
* Check in new manifest
* Run abc in a GH Actions workflow
```

### Additional information

_No response_