Kartodock local development and its CI are broken because postgresql.org dropped their stretch support. Upgrade to a supported postgresql 11 image if possible.

W: The repository 'http://apt.postgresql.org/pub/repos/apt stretch-pgdg Release' does not have a Release file.
E: Failed to fetch http://apt.postgresql.org/pub/repos/apt/dists/stretch-pgdg/11/binary-amd64/Packages 404 Not Found [IP: 147.75.85.69 80]