fix: update artifact name to correct arch for macOS runner image

For `macos-latest` runner image, the default architecture is `arm64`,
refer to the below link for more details:
- https://github.com/actions/runner-images/blob/macos-14/20250218.801/README.md#available-images
- https://docs.github.com/en/actions/using-github-hosted-runners/using-github-hosted-runners/about-github-hosted-runners#standard-github-hosted-runners-for-public-repositories

This change updates the artifact name to `darwin-arm64` to reflect the correct architecture.

.github/workflows/test.macos.yml

@@ -29,5 +29,5 @@ jobs:
       - name: Publish Build Artifacts
         uses: actions/upload-artifact@v4
         with:
-          name: darwin-amd64
+          name: darwin-arm64
           path: build/