Update actions/download-artifact action to v4

Author: renovate[bot]

.github/workflows/test.yml

@@ -66,7 +66,7 @@ jobs:
     needs: xcodebuild
     runs-on: macOS-13
     steps:
-      - uses: actions/download-artifact@v3
+      - uses: actions/download-artifact@v4
         with:
           path: test_output
       - name: Merge xcresult files