make gufw-pkexec more flexible

[LiohMoeller]

In order to make the gufw-pkexec script more flexible concerning Python versions, I would like to suggest to switch to the following content:

#!/bin/bash
LOCATION=$(python3 -c "import site; print(site.getsitepackages()[0])")/gufw/gufw.py

if [[ -e "$LOCATION" ]]; then
        python3 "$LOCATION" $1
fi

This would protect against minor changes e.g. from Python 3.6 to 3.7.

[costales (costales)]

Hi!
Thanks a lot for the code! I'll release for Gufw 20.04.
A hug!