Installing fudge is is using 'use_2to3' which is deprecated and not supported in setuptools>57.5
Note: there is an old pull request fudge-py/fudge#12 that would fix the issue, but I just realized that is not really maintained anymore. Perhaps consider moving to another mock framework.
I understand that you have most likely a lot of other stuff you're working on - so take it with a grain of salt. 😀 At least in my (rather complex) environment, I don't like pinning python itself of setuptools to a specific version, which makes it difficult integrate this in my work.