Bump actions/upload-artifact from v1 to v2.2.1 (#3936)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from v1 to v2.2.1.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v1...726a6dc)

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

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

.github/workflows/sphinx.yml

@@ -26,7 +26,7 @@ jobs:
       with:
         docs-folder: "doc/"
     # Create an artifact out of the generated HTML
-    - uses: actions/upload-artifact@v1
+    - uses: actions/upload-artifact@v2.2.1
       with:
         name: UserGuideHTML
         path: "doc/_build/html/"