chore(deps): update actions/upload-pages-artifact action to v4 (#34)

Author: MikuroXina

.github/workflows/deploy.yaml

@@ -55,7 +55,7 @@ jobs:
         run: mdbook build
 
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@v4
         with:
           path: ./build