textproc/utf8proc: Update to 2.8.0 and take maintainership

Take maintainership after multiple timeouts from current maintainer.

Changelog: https://github.com/JuliaStrings/utf8proc/releases/tag/v2.8.0

References:
https://reviews.freebsd.org/D33552
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=251357
https://reviews.freebsd.org/D20399

PR: 267592
Approved by: portmgr (maintainer timeout, 2+ weeks)