pmem() not working on python carts

[imsys]

I decided to patch the games I mentioned in #2841 to work on the latest version of TIC80. I got all of them working, I will publish them soon. In the game HexaPix, I got that working, but I was struggling to get the progress save to work, I know it was working in the past.
I started to debug it a bit, and it seems that the pythom pmem() implementations is not working. ( @blueloveTH )

So I got an AI to generate some pmem test carts:

pmem-test.py
pmem-py-test.tic.zip

Lua carts are working nicely, it seems it is just the python API. I did not have the time to do more comprehensive tests yet. It would be nice if someone else could test to check if the problem only happens on my side, or if it is really a problem in the API.

[blueloveTH]

I will investigate this soon.