Add the repository signing key
Import the public signing key for this organization. Run this command:
curl https://baltocdn.com/webhippie/signing.asc | sudo apt-key add -
Register the repository
Add the repository to your apt configuration.
Run these commands to add the repository and download the package indexes.
sudo apt-get install apt-transport-https --yes
echo "deb https://baltocdn.com/webhippie/promhippie/debian/ all main" | sudo tee /etc/apt/sources.list.d/webhippie-promhippie-debian.list
sudo apt-get update