ubuntu18.04配置python3.7, 更改pip3指向, 处理Python.h缺失，安装python3.7-dev.

更改pip3指向：https://blog.csdn.net/yiyu3344/article/details/90102410

  1、sudo rm /usr/bin/python3

  2、sudo ln -s /usr/bin/python3.7 /usr/bin/python3

处理Python.h缺失，安装python3.7-dev: https://packages.ubuntu.com/bionic-updates/amd64/python3.7-dev/download

  You should be able to use any of the listed mirrors by adding a line to your /etc/apt/sources.list like this:

      deb http://cz.archive.ubuntu.com/ubuntu bionic-updates main universe