Upgrade deprecated publishing plugin

The GitHub plugin used to publish pages has been deprecated and yanked
upstream; use a newer version.

Author: WhyNotHugo

.github/workflows/pages.yml

@@ -30,7 +30,7 @@ jobs:
       - run: sudo apt install hugo
       - run: hugo
       - uses: actions/configure-pages@v1
-      - uses: actions/upload-pages-artifact@v1
+      - uses: actions/upload-pages-artifact@v3
         with:
           path: public/