【Python】You are using pip version 9.0.1, however version 23.0.1 is available.

完整报错如下：

Cache entry deserialization failed, entry ignored
Could not fetch URL https://pypi.tuna.tsinghua.edu.cn/simple/pip/: There was a problem confirming the ssl certificate: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:748) - skipping
Requirement already up-to-date: pip in d:\anaconda3\envs\python36\lib\site-packages
You are using pip version 9.0.1, however version 23.0.1 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.

解决方案：换源安装，清华源不好使，换豆瓣源安装
代码如下：

python -m pip install --upgrade pip -i https://pypi.douban.com/simple

结果一次成功

(python36) C:\WINDOWS\system32>python -m pip install --upgrade pip -i https://pypi.douban.com/simple
Collecting pip
  Downloading https://pypi.doubanio.com/packages/a4/6d/6463d49a933f547439d6b5b98b46af8742cc03ae83543e4d7688c2420f8b/pip-21.3.1-py3-none-any.whl (1.7MB)
    100% |████████████████████████████████| 1.7MB 750kB/s
Installing collected packages: pip
  Found existing installation: pip 9.0.1
    Uninstalling pip-9.0.1:
      Successfully uninstalled pip-9.0.1
Successfully installed pip-21.3.1