Associate .py with python on Windows

Description:
Associate .py with python on Windows when running actions/setup-python@v4

Justification:
I want to test that my .py have executable permission set relying on shebang line. That passes on Ubuntu. Windows doesn't care about file permissions set by git, but it has a different mechanism:
https://docs.python.org/3/faq/windows.html#how-do-i-make-python-scripts-executable

On Windows, the standard Python installer already associates the .py extension with a file type (Python.File) and gives that file type an open command that runs the interpreter (D:\Program Files\Python\python.exe "%1" %*).

and https://docs.python.org/3/using/windows.html#from-file-associations:

The launcher should have been associated with Python files (i.e. .py, .pyw, .pyc files) when it was installed.

Apparently that doesn't happen when using actions/setup-python@v4

Are you willing to submit a PR?
No

从 actions/setup-python@v4 的 Windows 设置路径开始，并查看链接的关于 Windows 文件关联的 Python 文档。确认该 action 当前如何安装或提供 Python，然后验证使用 shebang 的 .py 脚本能否在 Windows action 中运行；完成的标准是该关联在其中能够一致地工作。