Bump actions/download-artifact from 7 to 8

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>

.github/workflows/assets.yml

@@ -79,7 +79,7 @@ jobs:
     if: github.event_name == 'push' && github.ref_name == github.event.repository.default_branch || github.event_name == 'workflow_dispatch'
     steps:
       - uses: actions/checkout@v6
-      - uses: actions/download-artifact@v7
+      - uses: actions/download-artifact@v8
         with:
           name: lila-assets
 

.github/workflows/server.yml

@@ -72,7 +72,7 @@ jobs:
       packages: write
     steps:
       - uses: actions/checkout@v6
-      - uses: actions/download-artifact@v7
+      - uses: actions/download-artifact@v8
         with:
           name: lila-server