security/botan2: Update to 2.12.0

Changes: https://botan.randombit.net/news.html#version-2-12-0-2019-10-07

Also bump PORTREVISION of dependent ports.

PR: 241217
Submitted by: Ralf van der Enden <tremere@cainites.net> (maintainer)
Approved by: tz (mentor)
Differential Revision: https://reviews.freebsd.org/D22000