Bump actions/download-artifact from 2.1.0 to 3

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 2.1.0 to 3.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](https://github.com/actions/download-artifact/compare/v2.1.0...v3)

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

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/tests.yml

@@ -138,7 +138,7 @@ jobs:
           nox --version
 
       - name: Download coverage data
-        uses: actions/download-artifact@v2.1.0
+        uses: actions/download-artifact@v3
         with:
           name: coverage-data