Add missing test dependency

.github/workflows/test.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          python -m pip install pytest
+          python -m pip install pytest assertpy
           python -m pip install .
           if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
       - name: Test with pytest