It appears that on GitHub Action's macos runner (and only there as far as I can tell) the actions user doesn't have permission to generate the virtual environment. Specifically, it appears that user is lacking write permission to the tmp directory created by pytest:
https://github.com/birdcar/devwrangler/runs/4724004981?check_suite_focus=true#step:5:168
To this I say: WAT 👀