update the dockerfile, test=doc

docker/ubuntu18-cpu/Dockerfile

 FROM registry.baidubce.com/paddlepaddle/paddle:2.2.2
 LABEL maintainer="paddlesl@baidu.com"
 
-RUN git clone https://github.com/PaddlePaddle/PaddleSpeech.git /home/PaddleSpeech 
-RUN pip3 uninstall mccabe -y; exit 0;
-RUN pip3 install multiprocess==0.70.12
-RUN pip3 install importlib-metadata==4.2.0
+RUN git clone --depth 1 https://github.com/PaddlePaddle/PaddleSpeech.git /home/PaddleSpeech  
+RUN pip3 uninstall mccabe -y ; exit 0;
+RUN pip3 install multiprocess==0.70.12 importlib-metadata==4.2.0 dill==0.3.4
 
 RUN cd /home/PaddleSpeech/audio
 RUN python setup.py bdist_wheel
-RUN pip install dist/*.whl
 
 RUN cd /home/PaddleSpeech
 RUN python setup.py bdist_wheel
-RUN pip install dist/*.whl
+RUN pip install audio/dist/*.whl dist/*.whl
 
 WORKDIR /home/PaddleSpeech/