fix build failure introduced by #218 -- tmp fix

.circleci/config.yml

@@ -32,7 +32,7 @@ jobs:
             python3 -m venv venv
             . venv/bin/activate
             pip install --upgrade pip
-            pip install -r requirements.txt
+            pip install -r requirements_ci.txt
             pip install conda
             pip install pytest
             pip install pytest-cov