Centos OS 8默认的Python版本为3.6，不符合练习的需求。现在升级到3.9。
# 下载Python3.9.9
wget https://www.python.org/ftp/python/3.9.9/Python-3.9.9.tgz
tar zxvf Python-3.9.9.tgz
# 安装必须的包
dnf -y install gcc zlib* libffi-devel
cd Python-3.9.9/
./configure --prefix=/usr/local/python3 --enable-optimizations
make
make install
# 删除原先的Python3和pip3
rm -rf /usr/bin/python3
ln -s /usr/local/python3/bin/python3 /usr/bin/python3
rm -rf /usr/bin/pip3
ln -s /usr/local/python3/bin/pip3 /usr/bin/pip3查看Python3和Pip3是否正确的被安装：
python3 --version
pip3 --version