I think Tensorflow 2.x is officially supported by upstream spleeter as of ~Oct 2020:
deezer/spleeter#498
I'm not fully familiar with how the pieces fit together, but as an Apple Mac M1 user, I think I (currently) need to use a special drop-in compatible version of Tensorflow 2.x, as otherwise I get illegal hardware instruction errors with the current TF 1.x usage:
https://github.com/apple/tensorflow_macos