net/libyang2: update to 2.1.128 fixes net/frr8 regression

[Franco Fichtner]

Hi,

Would a committer mind picking this up as it affects operation
of FRR ports and it's reached maintainer timeout state:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=274667

Quarterly is probably affected too.


Thanks,
Franco