For testing arrays is needed numpy, adding to yml file for succesfull…

…y run the workflow

.github/workflows/pytest.yml

@@ -29,6 +29,7 @@ jobs:
           python -m pip install --upgrade pip
           pip install .
           pip install pytest
+          pip install numpy
           
       - name: Run unit tests
         run: python -m pytest --import-mode=append tests/