Included the groupadd command to avoid group error

This MR is just a change in a line of the dockerfile to avoid an error. No need for a detailed review

\approve @ds

Dockerfile

@@ -35,7 +35,8 @@ RUN pip3 install shapely --upgrade
 
 COPY ./files/start.sh /usr/local/bin
 
-RUN  useradd -r -u 1000 -g appuser appuser
+RUN groupadd -g 1000 appuser &&\
+     useradd -r -u 1000 -g appuser appuser
 USER appuser
 
 CMD ["/usr/local/bin/start.sh"]