This script was used to backup all schema/database postgresql version 15 to the GCP, if you want to dump older version you need to change the postgres-client-15 to the version what you want on Dockerfile
For running on your local device use docker, just run docker compose up it will automatically build local docker images
If you are running on kubernetes, just apply the manifest kubectl -n namespace -f kubernetes-postgres-backup-k8s.yml apply