[aw] Update DefaultVersions.props failed

### Workflow Failure

**Workflow:** [Update DefaultVersions.props](https://github.com/dotnet/arcade/blob/main/.github/workflows/update-default-versions.md)
**Branch:** main
**Run:** https://github.com/dotnet/arcade/actions/runs/34668531132
**Pull Request:** [#12885](https://github.com/dotnet/arcade/pull/12885)

**⚠️ Engine Failure**: The `copilot` engine terminated unexpectedly.

**Last agent output:**
```
Authentication failed with provider at http://172.30.0.30:10002 (HTTP 401).
Check your COPILOT_PROVIDER_API_KEY or COPILOT_PROVIDER_BEARER_TOKEN.
Changes +0 -0
Duration 0s
```

### Action Required

**Assign this issue to an agent** to debug and fix the issue.

Debug with any coding agent

Use this prompt with any coding agent (GitHub Copilot, Claude, Gemini, etc.):

````
Debug the agentic workflow failure using https://raw.githubusercontent.com/github/gh-aw/main/debug.md

The failed workflow run is at https://github.com/dotnet/arcade/actions/runs/34668531132
````

Manually invoke the agent

Debug this workflow failure using your favorite Agent CLI and the `agentic-workflows` prompt.

- Start your agent
- Load the `agentic-workflows` skill from `.github/skills/agentic-workflows/SKILL.md` or
- Type `debug the agentic workflow update-default-versions failure in https://github.com/dotnet/arcade/actions/runs/34668531132`

> [!TIP]
>
> Stop reporting this workflow as a failure
>
> To stop a workflow from creating failure issues, set `report-failure-as-issue: false` in its frontmatter:
> ```yaml
> safe-outputs:
> report-failure-as-issue: false
> ```
>
>

> Generated from [Update DefaultVersions.props](https://github.com/dotnet/arcade/actions/runs/34668531132) · [◷](https://github.com/search?q=repo%3Adotnet%2Farcade+is%3Aissue+%22gh-aw-workflow-id%3A+update-default-versions%22&type=issues)
> - [x] expires on Sep 19, 2026, 2:47 AM UTC

Start with the failed Update DefaultVersions.props run and its workflow documentation at .github/workflows/update-default-versions.md. Read the agentic-workflows skill at .github/skills/agentic-workflows/SKILL.md and inspect the linked run's authentication failure. Done means the workflow can complete successfully without the copilot provider returning HTTP 401.

Written by the indexing model from the issue text.