package/z3: bump to version 4.12.1

For change log since v4.12.0, see:
- https://github.com/Z3Prover/z3/releases/tag/z3-4.12.1



Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>