Try to run this command from the system terminal. Make sure that you use the correct version of ‘pip’ installed for your Python interpreter located at ‘C:\Users\123\PycharmProjects\pythonProject\venv\Scripts\python.exe’.
出现这个问题的原因是安装的Python版本较新，还没有对应版本的pip，解决的办法是安装较旧的版本，笔者安装的是3.9版本，安装3.8版本这个问题就解决了。
这个截图的查看链接为Python and OS Compatibility