Try to fix tests.yml

Author: erezsh

.github/workflows/tests.yml

@@ -22,8 +22,9 @@ jobs:
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install pytest
+          pip install Cython
           python setup.py install
+          pip install pytest
       - name: Run tests
         run: |
           pytest