Print networkx version in CI for debugging purposes

.github/workflows/unit-build.yml

@@ -31,6 +31,8 @@ jobs:
         pip install .[docs]
         pip install .[profilers]
         pip install pytest-cov
+    - name: Print the installed version of networkx
+      run: pip show networkx | grep "Version"
     - name: Test with pytest
       run: |
         pytest --cov=golem test/unit