fix(ci): guard dual-approval job against null pull_request context

When triggered by pull_request_review events, github.event.pull_request
is undefined, which can cause issues when the job tries to access
github.event.pull_request.number. Add a job-level if guard to prevent
the job from running in these conditions.

This addresses the dual approval failures seen on feature branches where
the workflow was running without a valid PR context.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.github/workflows/dual-approval.yaml

@@ -14,6 +14,7 @@ on:
 
 jobs:
   dual-approval:
+    if: github.event.pull_request != null
     uses: privilegedescalation/.github/.github/workflows/dual-approval-check.yaml@main
     secrets: inherit
     with: