ci: Pin ghaction-github-pages to commit SHA (security hardening)

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: jparrabedoya

.github/workflows/docs.yml

@@ -21,7 +21,7 @@ jobs:
 
     - name: Deploy
       if: success()
-      uses: crazy-max/ghaction-github-pages@v5.0.0
+      uses: crazy-max/ghaction-github-pages@1d6ee9b181a81033a16bd707a1401afa978daab4 # v5.0.0
       with:
         target_branch: gh-pages
         build_dir: ./docs