Bump actions/download-artifact from 7 to 8 (#8851)

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 7 to 8.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](https://github.com/actions/download-artifact/compare/v7...v8)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '8'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/build-linux.yml

@@ -169,7 +169,7 @@ jobs:
         fetch-depth: '0'
 
     - name: Restore build artifacts
-      uses: actions/download-artifact@v7
+      uses: actions/download-artifact@v8
       with:
         name: v2rayN-linux
         path: ${{ github.workspace }}/v2rayN/Release