Update math/cadabra2 to 2.1.4

• Add patch patch-core_cadabra2.in, to get proper shebang in bin/cadabra2.

PR: 218985
Submitted by: Yuri Victorovich <yuri@rawbw.com>
Approved by: Yuri Victorovich (maintainer), rakuco (mentor, implicit)
Differential Revision: https://reviews.freebsd.org/D10761