pyarmor and python 3.9 and libpython

[colorado-bob]

Ubuntu 20.04.6 LTS
Python 3.9.5
Pyarmor 8.1.1 (trial), 000000, non-profits

the documentation says pyarmor is compatible with python 3.7 - 3.11
i am having an issue running python3.9.
**Is pyarmor compatible with python 3.9?

• if compatible, what am i doing wrong?**

running in a terminal:
ubuntu<...>/dist$ python3.9 test.py
Traceback (most recent call last):
File "", line 3, in
RuntimeError: this Python version is not supported (1:1106)

running in docker compose (only related items from files below):
dockerfile: FROM python:3.9.5-slim-buster as builder
docker-compose.yml: command: python3.9 test.py

devtest | Traceback (most recent call last):
devtest | File "/home/skos/test.py", line 2, in
devtest | from pyarmor_runtime_000000 import pyarmor
devtest | File "/home/skos/pyarmor_runtime_000000/init.py", line 2, in
devtest | from .pyarmor_runtime import pyarmor
devtest | ImportError: libpython3.8.so.1.0: cannot open shared object file: No such file or directory

if i change to python 3.8, it all works.
FROM python:3.8 as builder
python3.8 test.py