Fix referenced SHA

Author: dan-fernandes

.github/workflows/_push_docs.yml

@@ -31,7 +31,7 @@ jobs:
         if: github.ref_type == 'tag' || github.ref_name == 'main'
         # We pin to the SHA, not the tag, for security reasons.
         # https://docs.github.com/en/actions/learn-github-actions/security-hardening-for-github-actions#using-third-party-actions
-        uses: peaceiris/actions-gh-pages@3f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4.0.0
+        uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4.0.0
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: .github/pages