Installation on windows powershell fails

[hcoohb]

• I have searched the issue tracker and believe that this is not a duplicate.

Steps to reproduce

Run (Invoke-WebRequest -Uri https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py -UseBasicParsing).Content | python - into a powershell prompt.
Windows 10
Python 3.7.5

Actual behavior

PS C:\Users\Me>  (Invoke-WebRequest -Uri https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py -UseBasicParsing).Content | python
Installing PDM (1.10.0): Creating virtual environment
Installing PDM (1.10.0): Installing PDM and dependencies
Traceback (most recent call last):
  File "<stdin>", line 433, in <module>
  File "<stdin>", line 429, in main
  File "<stdin>", line 355, in install
  File "<stdin>", line 304, in _install
  File "<stdin>", line 45, in _call_subprocess
  File "C:\Users\Me\AppData\Local\Programs\Python\Python37\lib\subprocess.py", line 488, in run
    with Popen(*popenargs, **kwargs) as process:
  File "C:\Users\Me\AppData\Local\Programs\Python\Python37\lib\subprocess.py", line 800, in __init__
    restore_signals, start_new_session)
  File "C:\Users\Me\AppData\Local\Programs\Python\Python37\lib\subprocess.py", line 1148, in _execute_child
    args = list2cmdline(args)
  File "C:\Users\Me\AppData\Local\Programs\Python\Python37\lib\subprocess.py", line 555, in list2cmdline
    needquote = (" " in arg) or ("\t" in arg) or not arg
TypeError: argument of type 'WindowsPath' is not iterable

Expected behavior

Installation of pdm

Other details,

Adding some output to the _call_subprocess function, it seems it was called with the args being:
[WindowsPath('C:/Users/Me/AppData/Roaming/pdm/venv/Scripts/python.exe'), '-m', 'pip', 'install', 'pdm==1.10.0']
So maybe the call to _call_subprocess needs to be made with str(venv_python) (L 303)? and similarly on Line 342?

[frostming]

You are right, Python 3.7 doesn't support that usage.