pyseabreeze: implement gpio feature

[ap--]

Originally posted by @ap-- in https://github.com/ap--/python-seabreeze/discussions/132#discussioncomment-1353962

Referenced from the discussion section:

So to get this working you will need to implement the GPIO feature for the QEPro.
It's not really complicated to do so, and I have started a new branch: https://github.com/ap--/python-seabreeze/tree/qepro-gpio-wip for you where I sketched out the implementation for pyseabreeze: 3d0d32b

But I don't have a QEPro. So from this branch you should be able to continue implementing the GPIO feature and test it with your spectrometer. (It might already work. Just set gpio pin4 as an output and try toggeling it.)

Here is the command reference from the datasheet:

I hope that helps! It would be great if you could finish the implementation and make a pull request ❤️

Cheers
Andreas