TST: fix missing dep

.docker/Dockerfile

@@ -6,6 +6,7 @@ RUN apt-get update && \
     openjdk-11-jdk-headless \
     python3-autopep8 \
     python3-pip \
+    python3-pytest \
     tox \
     -y
 COPY .docker/wait-for-it.sh /wait-for-it.sh
@@ -33,4 +34,4 @@ CMD /wait-for-it.sh caosdb-server:10443 -t 500 -- \
     # ... install pycaosdb.ini the server-side scripts
     cp /git/.docker/sss_pycaosdb.ini /scripting/home/.pycaosdb.ini && \
     # ... and run tests
-    ./test.py
+    pytest .