x11/clipman: Update 1.6.4 => 1.6.5, take maintainership

Changelogs:

• https://github.com/chmouel/clipman/releases/tag/v1.6.5
• https://github.com/chmouel/clipman/compare/v1.6.4...v1.6.5

Approved by: yuri@ (Mentor)
Differential Revision: https://reviews.freebsd.org/D53042