pantalaimon in Debian has entered their testing suite, and we therefore no longer need to custom-build it for our byzantium suite.

Please therefore switch to track pantalaimon in Debian for byzantium.

This related to T938: If we supported ~pureos as deviation annotation in version string, the switch could happen today, but because our current package used +pureos annotation we can only switch when a newer release of pantalaimon enters testing (which in this concrete case should happen in few days).