textproc/py-Tempita: Fix build with py-setuptools 58.0.0+
> Configuring for py38-Tempita-0.5.2
error in Tempita setup command: use_2to3 is invalid.
- Error code 1
Stop.
make: stopped in /usr/ports/textproc/py-Tempita
Reference: https://github.com/pypa/setuptools/blob/main/CHANGES.rst