Add timeouts and status handling to GitHub workflow cancellation script

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Problem

scripts/cancel_github_workflows.py uses requests.request(...) without a timeout and assumes every response body can be parsed as JSON. In CI or local maintenance workflows this can hang indefinitely or hide HTTP status failures behind confusing JSON errors.

Proposed remediation

Make the GitHub API helper fail fast and report clearer errors.

Acceptance criteria

• Add a sensible request timeout for every GitHub API call.
• Call raise_for_status() or otherwise surface non-2xx responses before consuming the response body.
• Preserve the existing Click CLI behavior and error style.
• Add focused unit tests around the request() helper if practical.

Suggested validation

• python -m py_compile scripts/cancel_github_workflows.py
• Focused tests for successful JSON, API error message, non-JSON/HTTP error, and timeout behavior if a lightweight test location exists.

[outwrit]

Devin remediation automation started a session for this issue.

• Run: run-116100ce47a64b4fb57e96eef845fac4
• Devin session: https://app.devin.ai/sessions/badbd64442b14342a5d38abda73a4d8b
• Expected output: a pull request linked back to this issue, plus tests/validation in the session output.

[outwrit]

Devin remediation automation started a session for this issue.

• Run: run-3b3454f2334544808dabef35b40fa2ab
• Devin session: https://app.devin.ai/sessions/6c13f56bf4e841148a2f1e777c57597b
• Expected output: a pull request linked back to this issue, plus tests/validation in the session output.