Don't publish docs on PRs (#1596)

Author: martintmk

.github/workflows/gh-pages.yml

@@ -30,6 +30,7 @@ jobs:
     - run: dotnet docfx docs/docfx.json
 
     - name: Deploy
+      if: github.event_name != 'pull_request'
       # if: startsWith(github.ref, 'refs/tags/')
       uses: peaceiris/actions-gh-pages@v3
       with: