This port will be removed on 2020-12-31 if not fixed
You're right, and upstream knows the situation (same thing on many Linux distros).
They are working on gdl-v1.0.0, which will depend on Python 3.x.
v1.0.0-rc.3 has been out since June 19, but there remains some caveats:
Switched to Python 3.6+ (commented out) in r557839