pip版本升级

在安装PyCharm后，需要在“File”> "Settings"下的“Python Interpreter”里面添加安装pandas软件包，但是在安装pandas的过程中，PyCharm提示以下错误：

WARNING: You are using pip version **20.1.1**; however, version **21.0** is available.
You should consider upgrading via the '/dm/pythonProject/venv/bin/python -m pip install --upgrade pip' command.

根据提示“python -m pip install --upgrade pip”进行pip版本的升级，结果还是出现同样的错误：

......
pip._vendor.urllib3.exceptions.ReadTimeoutError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Read timed out.
WARNING: You are using pip version 20.1.1; however, version 21.0 is available.
You should consider upgrading via the '/dm/pythonProject/venv/bin/python -m pip install --upgrade pip' command.

通过指定专门的pip版本进行安装，成功完成了项目下pip的版本升级：

$ cd /dm/pythonProject/venv/bin/python
$ ./python -m pip install pip==21.0
$ ./python -m pip  --version
pip 21.0 from /dm/pythonProject/venv/lib/python3.8/site-packages/pip (python 3.8)