tweak: use v4 download-artifact

Author: g105b

.github/workflows/ci.yml

@@ -77,7 +77,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      - uses: actions/download-artifact@v3
+      - uses: actions/download-artifact@v4
         with:
           name: code-coverage-${{ matrix.php }}-${{ github.run_number }}
           path: _coverage