Bump actions/download-artifact from 2.0.10 to 2.1.0

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 2.0.10 to 2.1.0.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v2.0.10...v2.1.0)

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

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

Author: dependabot[bot]

.github/workflows/ci.yaml

@@ -256,7 +256,7 @@ jobs:
           echo "Failed to restore Python venv from cache"
           exit 1
       - name: Download all coverage artifacts
-        uses: actions/download-artifact@v2.0.10
+        uses: actions/download-artifact@v2.1.0
       - name: Combine coverage results
         run: |
           . venv/bin/activate