Feel free to support my work:
git clone https://github.com/MalteKiefer/invoicy
cd invoicy
pip3 install -r requirements.txt
sudo cp data/com.github.maltekiefer.invoicy.gschema.xml /usr/share/glib-2.0/schemas/
sudo glib-compile-schemas /usr/share/glib-2.0/schemas/
python3 src/main.py