That's right, the python tuner has officially been retired. It is not being actively maintained by anyone, and is out of date with the protocol requirements. The commit that introduces this new goodbye readme also removes all other files. If you're interested in resurrecting this project simply git reset --hard fdfeaac66152300d9833dba1b24f0ae26c467965 and start working on it! On behalf of the FreeEMS team we extend a big thank you to Aaron Barnes for his efforts on this project at a critical time in the firmware development process. Without his help we wouldn't be where we are now and we won't forget that contribution.
Please see https://github.com/djandruczyk/MegaTunix for the latest MTX code which is currently the tuning tool of choice for FreeEMS.