There is currently no new 20.1 package planned, thought you can change the tag 20.1
to 21.1.
and update to the new 21.1 release containing the fix:
cd /etc/egroupware-docker
sed 's/:20.1/:21.1/g' -i docker-compose.override.yml
docker-compose up -d
The container you get is (most likely) identical to the final 21.1 released on Tuesday.
Ralf