Okay, this will stop 98% of the programmers here from exploiting it (and will also stop the users that are too lasy to switch manually from playing the server).
The other 2% could take use of a simple python lib - sklearn - to train an neural net which can solve almost any image with ~97% correctness, depending on the training data.
Of course one can use any NN for it - or simply use one of the thousand web services that gladly resolve all your captchas for free (which may be much slower than using a NN). You can't really do anything (efficient) against this.
Captchas has been there for a long time and as such are not very reliable anymore (because lots of programmers tried to get rid of them during this time).
By the way, as soon as one has access to the python code, he can easily overwrite every check you implemented and just send it, except you have backend verification.
And even then, the client gets the code (as he must generate the image and display it), so one can tap in at this point (solution would be generation on a webserver).
I do not say it is a bad idea, I just want to show you some problems with the solution.
But as the past shows us, most servers without the ability of switchbotting just do not have that many players (there may be exceptions).
Happy coding :D
