BUG: Install packages for notebook tests

Author: thewtex

.github/workflows/notebook-test.yml

@@ -9,9 +9,26 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - uses: actions/setup-python@v2
+        with:
+          python-version: 3.8
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          python -m pip install --upgrade setuptools wheel
+          pip install -r requirements.txt -r requirements-dev.txt PySide2
+      - name: Install package and extension
+        run: |
+          python -m pip install -e .
+          jupyter nbextension install --py --symlink --sys-prefix itkwidgets
+          jupyter nbextension enable --py --sys-prefix itkwidgets
+          jupyter nbextension enable --py --sys-prefix widgetsnbextension
+        env:
+          MPLBACKEND: Qt5Agg
       - uses: treebeardtech/[email protected]
         with:
           docker-username: "${{ secrets.DOCKER_USERNAME }}"
           docker-password: "${{ secrets.DOCKER_PASSWORD }}"
           docker-image-name: insighttoolkit/itkwidgets
           notebooks: examples/*.ipynb
+        env:
+          MPLBACKEND: Qt5Agg