fix(preview): rerun workflow only for relevant label events

Agent-Logs-Url: https://github.com/UCD-SERG/qwt/sessions/238dabae-dc52-4ab8-a965-309d223855c8

Co-authored-by: d-morrison <2474437+d-morrison@users.noreply.github.com>

Author: Copilot

.github/workflows/preview.yml

@@ -12,6 +12,9 @@ on:
 
 jobs:
   build-deploy:
+    if: |
+      (github.event.action != 'labeled' && github.event.action != 'unlabeled') ||
+      contains(fromJson('["revealjs","pdf","docx","no-preview-highlights"]'), github.event.label.name)
     runs-on: ubuntu-latest
     permissions:
       contents: write