Unable to launch wattmanGTK

[rijndael86]

Each time I launch through terminal I get this:

Traceback (most recent call last):
  File "/usr/bin/wattmanGTK", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3251, in <module>
    def _initialize_master_working_set():
  File "/usr/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3234, in _call_aside
    f(*args, **kwargs)
  File "/usr/lib/python3.8/site-packages/pkg_resources/__init__.py", line 3263, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/lib/python3.8/site-packages/pkg_resources/__init__.py", line 583, in _build_master
    ws.require(__requires__)
  File "/usr/lib/python3.8/site-packages/pkg_resources/__init__.py", line 900, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python3.8/site-packages/pkg_resources/__init__.py", line 786, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'WattmanGTK==0.0.1' distribution was not found and is required by the application

This happens since I updated to Python 3.8. Running Arch Linux (5.3).