Revert changes in building onnx on gpu (build on buster, not on ubuntu16)

Author: alonre24

opt/build/onnxruntime/Dockerfile.x64

@@ -10,18 +10,10 @@ ARG ONNXRUNTIME_VER=1.7.1
 ARG ARCH=x64
 
 RUN apt-get -qq update
-RUN apt-get install -y software-properties-common
-RUN add-apt-repository ppa:deadsnakes/ppa
-RUN apt-get -qq update
-
-RUN apt-get -qq install -y python3.6 curl wget tar git \
+RUN apt-get -qq install -y curl wget tar git \
             build-essential cmake \
             libcurl4-openssl-dev libssl-dev libatlas-base-dev zlib1g-dev \
             python3 python3-pip python3-dev python3-numpy
-
-RUN rm /usr/bin/python3
-RUN ln -s /usr/bin/python3.6 /usr/bin/python3
-
 RUN pip3 install --upgrade pip setuptools wheel
 
 ENV LANG=en_US.UTF-8

opt/build/onnxruntime/Dockerfile.x64-gpu

@@ -1,26 +1,19 @@
-ARG OS=ubuntu16.04
+ARG OS=ubuntu18.04
 ARG CUDA_VER=11.0-cudnn8
 
-FROM nvidia/cuda:11.0-cudnn8-devel-ubuntu16.04
+FROM nvidia/cuda:11.0-cudnn8-devel-ubuntu18.04
 
 ARG ONNXRUNTIME_REPO=https://github.com/RedisAI/onnxruntime
 ARG ONNXRUNTIME_VER=1.7.1
 ARG ARCH=x64-gpu
 
 RUN apt-get -qq update
-RUN apt-get install -y software-properties-common
-RUN add-apt-repository ppa:deadsnakes/ppa
-RUN apt-get -qq update
-
-RUN apt-get -qq install -y python3.6 curl \
+RUN apt-get -qq install -y curl \
             wget tar git build-essential \
             libcurl4-openssl-dev libssl-dev \
             libatlas-base-dev zlib1g-dev python3 python3-pip \
             python3-dev python3-numpy rsync
 
-RUN rm /usr/bin/python3
-RUN ln -s /usr/bin/python3.6 /usr/bin/python3
-
 RUN pip3 install --upgrade pip setuptools wheel
 
 RUN wget -q https://github.com/Kitware/CMake/releases/download/v3.19.5/cmake-3.19.5-Linux-x86_64.tar.gz -O /tmp/cmake.tgz
@@ -42,7 +35,7 @@ ARG BUILDARGS="--config ${BUILDTYPE} --parallel"
 
 RUN git clone --single-branch --branch rel-${ONNXRUNTIME_VER} ${ONNXRUNTIME_REPO} onnxruntime
 WORKDIR /build/onnxruntime
-RUN git fetch --recurse-submodules
+RUN git fetch --recurse-submodules -j4
 RUN ./build.sh ${BUILDARGS} --update --build --use_cuda --cudnn_home /usr/local/cuda --cuda_home /usr/local/cuda --build_shared_lib --parallel
 
 ADD ./pack.sh /build/