heroku run 创建一次性Dyno并在其中运行您的命令，您的更改将不会保留.

heroku run creates an one-off Dyno and runs your command in it, your changes wouldn't be persisted.

您实际上不需要自己进行 pip安装.此处为文档

You actually don't need to pip install yourself. Doc here

要通过pip在Heroku上指定Python包依赖关系，请添加一个pip需求文件，命名为requirements.txt到您的根目录存储库.

To specify Python package dependencies on Heroku via pip, add a pip requirements file named requirements.txt to the root of your repository.