Bump actions/upload-pages-artifact from 1 to 2 (#533)

Bumps [actions/upload-pages-artifact](https://github.com/actions/upload-pages-artifact) from 1 to 2.
- [Release notes](https://github.com/actions/upload-pages-artifact/releases)
- [Commits](actions/upload-pages-artifact@v1...v2)

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

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

.github/workflows/gh-pages.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Install doc build deps and build with Sphinx
         run: make docs
       - name: Upload artifacts
-        uses: actions/upload-pages-artifact@v1
+        uses: actions/upload-pages-artifact@v2
         with:
         # Upload built docs
           path: ./Documentation