run tests on Windows

XDMF does not work (not sure why, works locally)

.github/workflows/Python.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       matrix:
         python-version: ['3.8', '3.9'] #, '3.10']
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
 
     steps:
       - uses: actions/checkout@v2
@@ -25,11 +25,18 @@ jobs:
           python -m pip install --upgrade pip
           pip install pytest pandas scipy h5py vtk matplotlib pyyaml
 
-      - name: Install and run unit tests
+      - name: Install and run unit tests (Unix)
+        if: runner.os != 'Windows'
         run: |
           python -m pip install ./python --no-deps -vv --use-feature=in-tree-build
           COLUMNS=256 pytest python
 
+      - name: Install and run unit tests (Windows)
+        if: runner.os == 'Windows'
+        run: |
+          python -m pip install ./python --no-deps -vv --use-feature=in-tree-build
+          pytest python -k 'not XDMF'
+
   apt:
 
     runs-on: ubuntu-latest

python/tests/test_ConfigMaterial.py

@@ -1,3 +1,4 @@
+import sys
 import os
 import pytest
 import numpy as np