python3升级pip3

You are using pip version 9.0.1, however version 9.0.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

正确姿势

python3 -m pip install --upgrade pip

错误1

pip3 install --upgrade pip

错误2

pip3 install --upgrade pip3

坑

升级完成后pip默认是pip3了，如果要为python2.7添加库，需要pip2 install -U coremltools这么使用