Bump actions/upload-pages-artifact from 2 to 3 (#8)

Bumps [actions/upload-pages-artifact](https://github.com/actions/upload-pages-artifact) from 2 to 3.
- [Release notes](https://github.com/actions/upload-pages-artifact/releases)
- [Commits](actions/upload-pages-artifact@v2...v3)

.github/workflows/deploy.yml

@@ -21,7 +21,7 @@ jobs:
         run: make build
 
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v2
+        uses: actions/upload-pages-artifact@v3
         with:
           path: ./book