deskutils/sigi: Update 3.7.1 => 3.8.0

While here, update WWW and maintainer address.

Changelog:
https://github.com/so-dang-cool/sigi/releases/tag/v3.8.0

PR: 297449
Reported by: J.R. Hill <justin@so.dang.cool> (maintainer)
Approved by: osa, vvd (Mentors, implicit)