install scipy for tests

Author: nschloe

.circleci/config.yml

@@ -19,7 +19,7 @@ jobs:
       - run: apt update
       # <https://stackoverflow.com/a/44333806/353337>
       - run: DEBIAN_FRONTEND=noninteractive apt install tzdata
-      - run: apt install -y texlive-latex-base texlive-latex-extra python3-pip python3-tk
+      - run: apt install -y texlive-latex-base texlive-latex-extra python3-pip python3-tk python3-scipy
       - run: pip3 install -U pytest pytest-cov excode
       - checkout
       - run: cd ~/work