gns3 source packages on debian seems to be broken (you can run "sudo apt search gns3" to verify it) so you're only way to have gns3 on debian bookworm is to install it over PyPi packages and activate it using python virtual environment, take look at the part installing from PyPi in https://docs.gns3.com/docs/getting-started/installation/linux/.
You can also explore installation options on docker.
If nothing works for you take a look at eve-ng it's a powerful simulator like gns3, with a free version.
gns3 source packages on debian seems to be broken (you can run "sudo apt search gns3" to verify it) so you're only way to have gns3 on debian bookworm is to install it over PyPi packages and activate it using python virtual environment, take look at the part installing from PyPi in https://docs.gns3.com/docs/getting-started/installation/linux/. You can also explore installation options on docker. If nothing works for you take a look at eve-ng it's a powerful simulator like gns3, with a free version.