Bump actions/upload-artifact from 2.2.2 to 2.2.4 (#227)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 2.2.2 to 2.2.4.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v2.2.2...v2.2.4)

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

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

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

.github/workflows/tests.yml

@@ -85,14 +85,14 @@ jobs:
 
       - name: Upload coverage data
         if: always() && matrix.session == 'tests'
-        uses: "actions/upload-artifact@v2.2.2"
+        uses: "actions/upload-artifact@v2.2.4"
         with:
           name: coverage-data
           path: ".coverage.*"
 
       - name: Upload documentation
         if: matrix.session == 'docs-build'
-        uses: actions/upload-artifact@v2.2.2
+        uses: actions/upload-artifact@v2.2.4
         with:
           name: docs
           path: docs/_build