Bump actions/download-artifact from 4.1.8 to 4.1.9

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 4.1.8 to 4.1.9.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v4.1.8...v4.1.9)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -254,7 +254,7 @@ jobs:
       - name: Install dependencies
         run: pip install -U -r requirements_minimal.txt
       - name: Download all coverage artifacts
-        uses: actions/[email protected].8
+        uses: actions/[email protected].9
       - name: Combine Linux coverage results
         run: |
           coverage combine coverage-linux*/.coverage