chore: fix app.Dockerfile

Author: NGPixel

docker/app.Dockerfile

@@ -11,7 +11,7 @@ COPY docker/scripts/app-setup-debian.sh /tmp/library-scripts/docker-setup-debian
 RUN sed -i 's/\r$//' /tmp/library-scripts/docker-setup-debian.sh && chmod +x /tmp/library-scripts/docker-setup-debian.sh
 
 # Add Postgresql Apt Repository to get 14    
-RUN echo "deb http://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" | tee /etc/apt/sources.list.d/pgdg.list
+RUN echo "deb http://apt.postgresql.org/pub/repos/apt $(. /etc/os-release && echo "$VERSION_CODENAME")-pgdg main" | tee /etc/apt/sources.list.d/pgdg.list
 RUN wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | apt-key add -
 
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \