Update Dockerfile

Author: nullbutt

build/docker/jupyterlab/Dockerfile

@@ -50,4 +50,4 @@ RUN apt-get install -y r-base-dev && \
 EXPOSE 8888
 
 WORKDIR ${SHARED_WORKSPACE}
-CMD jupyter lab --ip=0.0.0.0 --port=8888 --no-browser --allow-root --NotebookApp.token='testing'
+CMD jupyter lab --ip=0.0.0.0 --port=8888 --no-browser --allow-root --NotebookApp.token=testing