Bump actions/download-artifact from 4 to 8 (#229)

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

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

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -184,7 +184,7 @@ jobs:
     # This job runs on Linux
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/download-artifact@v4
+    - uses: actions/download-artifact@v8
       with:
         path: artifacts
     - uses: actions/setup-python@v6