Update jekyll-gh-pages.yml

Link replacement should only affect html files, so as to not corrupt other files like a images

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

@@ -40,7 +40,7 @@ jobs:
         with:
           find: ".md"
           replace: ".html"
-          include: "_site/**"
+          include: "_site/**/*.html"
           regex: true
       - name: Upload artifact
         uses: actions/upload-pages-artifact@v2