Using csvkit with Python3.9 produces DeprecationWarning's

When running csvkit tools using Python 3.9, there's a ton of warnings:

$ python --version
Python 3.9.2
$ csvsql ...
/usr/lib/python3.9/site-packages/packaging/version.py:127: DeprecationWarning: Creating a LegacyVersion has been deprecated and will be removed in the next major release

I tried to disable the warnings with the following, but it doesn't help:

PYTHONWARNINGS="ignore::DeprecationWarning" csvsql