use ubuntu:16.04 in Dockerfile

Dockerfile

@@ -25,8 +25,8 @@ RUN apt-get install -y --no-install-recommends \
         g++-arm-linux-gnueabi \
         gcc-arm-linux-gnueabi
 RUN apt-get autoremove -y && apt-get clean
-RUN pip install wheel pre-commit
-RUN pre-commit autoupdate
+RUN pip install --upgrade pip
+RUN pip install wheel && pip install pre-commit
 RUN ln -s clang-format-5.0 /usr/bin/clang-format
 #RUN cd /tmp && curl -O http://mirrors.neusoft.edu.cn/android/repository/android-ndk-r17b-linux-x86_64.zip
 #RUN cd /opt && unzip /tmp/android-ndk-r17b-linux-x86_64.zip