devel/notcurses: Update to 2.1.0

Changelog: https://github.com/dankamongmen/notcurses/releases/tag/v2.1.0

PR: 251799
Submitted by: Nick Black <nickblack@linux.com> (maintainer)
Approved by: arrowd (mentor)
Differential Revision: https://reviews.freebsd.org/D27594