Cnpip

What's Changed
* Refactor/v1.2.0 by caoergou in https://github.com/caoergou/cnpip/pull/3
* add westlake mirror by andrewfowlie in https://github.com/caoergou/cnpip/pull/5

New Contributors
* caoergou made their first contribution in https://github.com/caoergou/cnpip/pull/3
* andrewfowlie made their first contribution in https://github.com/caoergou/cnpip/pull/5

**Full Changelog**: https://github.com/caoergou/cnpip/compare/v1.2.0...v1.2.1

- [x] 优化修改config的方式，直接使用pip自身命令来进行修改镜像，避免不同操作系统可能存在的差异.
- [x] 优化测速逻辑，提升测速速度
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English Version Description

- [x] Optimize the way of modifying config, directly use pip's own command to modify the image, to avoid possible differences between different operating systems
- [x] Optimize the logic of speed measurement, to improve the speed measurement speed

Full Changelog: https://github.com/caoergou/cnpip/compare/v1.1.0...v1.2.0

- [x] use aiohttp to test speed if possible

- [x] refactor: import mirrors from `py` file for speed.