Remove use of shell in subprocess call

[gnodar01]

• Resolves issue zmk code just opens root #27
• use of shell=True requires a string, not a list, and also has some security considerations: https://docs.python.org/3.10/library/subprocess.html#security-considerations

This fixes it for myself, but there may have been a good reason for using shell=True, so understandable if this simple "fix" isn't suitable.

[joelspadin]

IIRC, the reason for shell=True was so that you didn't have to specify the full path of the editor, e.g.

zmk config core.editor "code"

Does this work without the full path specified?

[joelspadin]

On Windows, removing shell=True does not work when the editor command does not use the full path. It calls _winapi.CreateProcess() which does not appear to search PATH for the program, so this results in a FileNotFoundError instead.

[joelspadin]

With

zmk config core.editor "code"

running zmk code with this change on Windows results in a FileNotFoundError. With shell=False, this calls _winapi.CreateProcess(), which doesn't search the PATH for the program.