Instructions
Replace your /etc/apt/sources.list contents to one of these sections
[Debian 13]
deb http://repo.iut.ac.ir/debian/ trixie main
deb http://repo.iut.ac.ir/debian/ trixie-updates main
[Debian 12]
deb http://repo.iut.ac.ir/debian/ bookworm main
deb http://repo.iut.ac.ir/debian/ bookworm-updates main
[Debian 11]
deb http://repo.iut.ac.ir/debian/ bullseye main
deb http://repo.iut.ac.ir/debian/ bullseye-updates main