Use pipenv instead of pip

Use pipenv instead of pip

pipenv[1] is the officially recommended Python packaging tool from Python.org[2]

[1]: https://docs.pipenv.org/
[2]: https://packaging.python.org/new-tutorials/installing-and-using-packages/

It integrates pip with virtualenv and handles version management better than pip.

Change-Id: I4ec6436e29d76a866b56caa609e2bcd22489ae9f
Signed-off-by: Yujun Zhang <zhang.yujunz@zte.com.cn>