Fix stale workflow authentication using GITHUB_TOKEN

[Copilot]

The stale issues workflow fails with "Parameter token or opts.auth is required" because secrets.YARNBOT_TOKEN doesn't exist in this forked repository.

Changes

• Updated .github/workflows/stale-workflow.yml to use secrets.GITHUB_TOKEN instead of secrets.YARNBOT_TOKEN

GITHUB_TOKEN is automatically provisioned by GitHub Actions with sufficient permissions for issue management.

- uses: actions/stale@v6
  with:
-   repo-token: ${{secrets.YARNBOT_TOKEN}}
+   repo-token: ${{secrets.GITHUB_TOKEN}}

Original prompt

Pull Request: https://github.com/Sawsqr68/berry_s/pull/6/files

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