fix(deps): refresh stale staged QPK pin branches

[Pigbibi]

Summary

• When a fully validated staged QPK pin PR is behind main, request the GitHub branch update API instead of attempting a stale merge.
• Let the updated branch run CI again before the existing restricted guard queues auto-merge.
• Keep the same same-repo, single-file, SHA, and main-history trust checks.

Validation

• Manually invoked all cases in tests/test_update_qpk_pin_workflow.py because pytest is unavailable on this VPS.
• Ran git diff --check.

No runtime target, deployment, or trading configuration is changed.