mac pip 安装插件后不在自己设置的目录，如何解决 Defaulting to user installation because normal site-packages is not writeable

1、使用命令 

python3 -m site --user-site

/Users/nxy/Library/Python/3.9/lib/python/site-packages

2、安装插件

pip3 install pytz
Defaulting to user installation because normal site-packages is not writeable
Requirement already satisfied: pytz in /Library/Python/3.7/site-packages (2022.1)

3、解决方案：

python3 -m pip install --upgrade pip
DEPRECATION: Configuring installation scheme with distutils config files is deprecated and will no longer work in the near future. If you are using a Homebrew or Linuxbrew Python, please see discussion at https://github.com/Homebrew/homebrew-core/issues/76621
Requirement already satisfied: pip in /usr/local/lib/python3.9/site-packages (22.1.1)
Collecting pip
  Downloading pip-22.1.2-py3-none-any.whl (2.1 MB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 2.1/2.1 MB 34.7 kB/s eta 0:00:00
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 22.1.1
    Uninstalling pip-22.1.1:
      Successfully uninstalled pip-22.1.1

4、再次安装发现神奇的好了

pip3 install pytz                   
DEPRECATION: Configuring installation scheme with distutils config files is deprecated and will no longer work in the near future. If you are using a Homebrew or Linuxbrew Python, please see discussion at https://github.com/Homebrew/homebrew-core/issues/76621
Collecting pytz
  Downloading pytz-2022.1-py2.py3-none-any.whl (503 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 503.5/503.5 kB 42.4 kB/s eta 0:00:00
Installing collected packages: pytz
  DEPRECATION: Configuring installation scheme with distutils config files is deprecated and will no longer work in the near future. If you are using a Homebrew or Linuxbrew Python, please see discussion at https://github.com/Homebrew/homebrew-core/issues/76621
DEPRECATION: Configuring installation scheme with distutils config files is deprecated and will no longer work in the near future. If you are using a Homebrew or Linuxbrew Python, please see discussion at https://github.com/Homebrew/homebrew-core/issues/76621
Successfully installed pytz-2022.1