test_run: support spaces in sys.executable path

[tomjakubowski]

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On my Mac, hatch creates its virtual environments in $HOME/Library/Application Support. So the python3 executable ends up at a path with a space in it.

The space in the path caused test_run() to fail, because without quotes the first utis.run() call would try and execute $HOME/Library/Application (up to the space) instead of the python3 executable.

[tomjakubowski]

This was kind of an obscure error. Let me know if I can explain it better.