chore: Bump flags-project-board workflow pin to latest

[haacked]

Re-pins the reusable flags-project-board.yml workflow to the latest main (d8b55d0).

This pulls in:

• The team→board mapping moving to a runtime config file (.github/flags-boards.json), so future board-list edits no longer require callers to re-pin.
• Removal of the dead direct pull_request_review trigger in the .github repo (no behavior change for callers).

No input contract changes — pr_number, pr_node_id, is_draft, and secrets: inherit are unchanged.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "Bump flags-project-board workflow pin to..." | Re-trigger Greptile}