How can I install the package python-uniconverter under ubuntu 19.10?

You can download this package manually from https://packages.ubuntu.com/xenial/python-uniconvertor and install with following commands:

cd ~/Downloads
wget http://archive.ubuntu.com/ubuntu/pool/universe/p/pillow/python-imaging_3.1.2-0ubuntu1.4_all.deb \
http://old-releases.ubuntu.com/ubuntu/pool/universe/p/python-reportlab/python-reportlab-accel_3.5.23-1ubuntu0.1_amd64.deb \
http://security.ubuntu.com/ubuntu/pool/universe/p/python-reportlab/python-reportlab_3.3.0-1ubuntu0.1_all.deb \
http://archive.ubuntu.com/ubuntu/pool/universe/p/python-uniconvertor/python-uniconvertor_1.1.5-2_amd64.deb
sudo apt install ./python-imaging_3.1.2-0ubuntu1.4_all.deb \
./python-reportlab-accel_3.5.23-1ubuntu0.1_amd64.deb \
./python-reportlab_3.3.0-1ubuntu0.1_all.deb \
./python-uniconvertor_1.1.5-2_amd64.deb