Bump actions/download-artifact from 4.1.7 to 4.1.8

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 4.1.7 to 4.1.8.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v4.1.7...v4.1.8)

---
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/tests.yaml

@@ -105,7 +105,7 @@ jobs:
             ${{ runner.os }}-${{ steps.python.outputs.python-version }}-${{
             needs.tests-linux.outputs.python-key }}
       - name: Download all coverage artifacts
-        uses: actions/[email protected].7
+        uses: actions/[email protected].8
       - name: Combine coverage results
         run: |
           . venv/bin/activate