Fix python-server dockerfile

The working directory shall be writeable to clone the pv repository.

PythonServer/Dockerfile

@@ -13,6 +13,8 @@ RUN conda update -n base conda \
   && conda clean -tipsy
 
 COPY --chown=csi:csi pos-python-server.py /app/
+# Make sure the /app directory is owned by csi
+RUN chown -R csi:csi /app
 WORKDIR /app
 
 USER csi