fix(ci): repair Dependabot auto-merge workflow

[sozercan]

Summary

• replace unsupported gh pr checks JSON fields with the supported workflow and bucket fields
• wait for every non-auto-merge check to finish and reject failed or cancelled checks
• remove the unnecessary approval command, which repository Actions settings do not permit
• identify Dependabot PRs by author and branch prefix rather than the event actor
• cancel stale per-PR workflow runs and require the merged head SHA to match the commit that was checked

Root cause

The workflow requested the unsupported status and conclusion fields from gh pr checks. GitHub CLI exited during argument validation, so the polling loop never ran and the merge step was always skipped. After correcting that query, the subsequent gh pr review --approve command would also have failed because Actions is not allowed to approve pull requests in this repository.

Impact

Dependabot PRs with successful CI can be merged automatically again. Stale runs cannot merge a newer, untested revision of a PR.

Validation

• actionlint .github/workflows/*.yml
• live polling query against Dependabot PR deps: bump github.com/Azure/azure-sdk-for-go/sdk/azcore from 1.21.0 to 1.22.0 #26 returned pass
• polling state-machine fixtures covered empty, pending, passing, skipped, failed, cancelled, and self-check scenarios
• make build
• go test ./... -count=1
• go vet ./...
• golangci-lint run ./...

[Copilot]

Pull request overview

Repairs Dependabot auto-merging while preventing stale workflow runs from merging untested revisions.

Changes:

• Corrects CI-check polling and failure handling.
• Detects Dependabot PRs reliably and cancels stale runs.
• Removes approval and verifies the checked head SHA before merging.

Show a summary per file

File	Description
.github/workflows/auto-merge.yml	Updates Dependabot validation, check polling, concurrency, and merge safeguards.

Review details

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• Files reviewed: 1/1 changed files
• Comments generated: 1
• Review effort level: Balanced

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: 139712b26c

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[sozercan]

@codex review

[Copilot]

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. What shall we delve into next?

Reviewed commit: 06b1fc5b07

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