DSA-6412-1 botan3 - security update

Multiple security issues were discovered in Botan, a C++ cryptography
library, which could result in denial of service, certificate validation
bypass or authentication bypass.

These issues have been addressed by updating botan3 to the new upstream
release 3.12.0. As a consequence this update changes the SONAME of the
shared library, and the runtime library package is renamed from
libbotan-3-7 to libbotan-3-12. No package in the stable distribution links
against the library, so no other packages in trixie are affected by this
change.

The libbotan-3-7 package is no longer built and will not be removed
automatically on upgrade if it had been installed manually. Locally built
or third-party software linking against libbotan-3-7 needs to be rebuilt
against libbotan-3-12, after which the old library package can be removed.

https://security-tracker.debian.org/tracker/DSA-6412-1