升级基础镜像 (#3544)

ci_scripts/Dockerfile

@@ -1,12 +1,9 @@
-ARG BASEIMAGE=registry.baidubce.com/paddleopen/paddle:build-gpu-cuda10.2-cudnn8-devel-ubuntu18.04-gcc8
+ARG BASEIMAGE=registry.baidubce.com/paddleopen/paddle:build-gpu-cuda10.2-cudnn8-devel-ubuntu18.04-gcc8-py38
 FROM ${BASEIMAGE}
 
 RUN git config --global user.name "PaddleCI" \
  && git config --global user.email "paddle_ci@example.com"
 
-RUN update-alternatives --install /usr/bin/python python /usr/bin/python3 10 \
- && update-alternatives --install /usr/bin/pip pip /usr/bin/pip3 10
-
 RUN apt-get update \
  && apt-get install -yq --no-install-recommends \
     wget \
@@ -15,7 +12,6 @@ RUN apt-get update \
  && rm -rf /var/lib/apt/lists/*
 
 # ci's requirements
-RUN pip3 install --no-cache-dir -i https://mirror.baidu.com/pypi/simple setuptools
 RUN echo 'docutils\n\
 scipy\n\
 prettytable\n\
@@ -37,7 +33,7 @@ urllib3\n\
 certifi\n\
 chardet\n\
 requests\n\
-decorator\n\
+decorator==4.4.2\n\
 astor' >paddle.requirements && \
     pip3 install --no-cache-dir -i https://mirror.baidu.com/pypi/simple -r paddle.requirements && \
     rm paddle.requirements