docs: Update upload-artifact to v3 in docs workflow

.github/workflows/main.yml

@@ -147,7 +147,7 @@ jobs:
           sudo apt install -y graphviz=2.42.2-6 pandoc=2.9.2.1-3ubuntu2 qtbase5-dev=5.15.3+dfsg-2ubuntu0.2 qt5-qmake=5.15.3+dfsg-2ubuntu0.2
       - name: Build Docs
         run: tox -edocs
-      - uses: actions/upload-artifact@v2
+      - uses: actions/upload-artifact@v3
         with:
           name: html_docs
           path: docs/_build/html