Appimage support

[nihilox]

Steps to reproduce

curl -L https://github.com/niess/python-appimage/releases/download/python3.10/python3.10.4-cp310-cp310-manylinux2014_x86_64.AppImage -o python3.10
mv python3.10 /usr/local/bin
curl -sSL https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py | /usr/local/bin/python3.10 -

Actual behavior

Installing PDM (1.14.1): Creating virtual environment
Installing PDM (1.14.1): Installing PDM and dependencies
An error occurred when executing ['~/.local/share/pdm/venv/bin/python', '-m', 'pip', 'install', '-IU', 'pip']:
~/.local/share/pdm/venv/bin/python: No module named pip

Expected behavior

https://python-appimage.readthedocs.io/en/latest/#using-a-virtual-environement

python -m ensurepip