Correct step name.

Author: samcunliffe

.github/workflows/doxygen-gh-pages.yml

@@ -66,7 +66,7 @@ jobs:
     if: github.event_name == 'push' && github.ref_name == 'main'
     environment:
       name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
+      url: ${{ steps.github-pages.outputs.page_url }}
     runs-on: ubuntu-latest
     needs: doxygen
     steps: