Upgrade download-artifact action to v4

Author: ColmN-Dev

.github/workflows/deploy.yml

@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Download build artifacts
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: astro-build
           path: dist