Bump action versions.

This matches a change in mystmd.

Author: ryanlovett

.github/workflows/deploy.yml

@@ -39,9 +39,9 @@ jobs:
       - name: Build HTML Assets
         run: myst build --html
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v1
+        uses: actions/upload-pages-artifact@v3
         with:
           path: './_build/html'
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v2
+        uses: actions/deploy-pages@v4