Update Dockerfile

Author: collabnix

sample/producer-consumer/Dockerfile

@@ -51,5 +51,5 @@ RUN wget https://github.com/opencv/opencv/archive/${OPENCV_VERSION}.zip \
 RUN ln -s \
   /usr/local/python/cv2/python-3.7/cv2.cpython-37m-x86_64-linux-gnu.so \
   /usr/local/lib/python3.7/site-packages/cv2.so
-RUN git clone https://github.com/collabnix/pico
+RUN git clone https://github.com/collabnix/pico \
   && cd pico/kafka/