fix windows tests

.github/workflows/python-tests.yml

@@ -28,7 +28,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           python -m pip install flake8 pytest
-          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+          pip install -r requirements.txt
       - name: Lint with flake8
         run: |
           # stop the build if there are Python syntax errors or undefined names