Update actions/download-artifact to v4 in deploy.yml. (#131)

Author: ezio-melotti

.github/workflows/deploy.yml

@@ -64,7 +64,7 @@ jobs:
 
     steps:
       - name: Download packages built by build-and-inspect-python-package
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: Packages
           path: dist