Port gnome-doc-utils to python3

Summary:
Packager notes:

• Port to python3
• Use correct homepage
• Fix the license

Signed-off-by: Algent Albrahimi <algent@protonmail.com>

Test Plan: Run yelp.

Reviewers: Triage Team, JoshStrobl

Reviewed By: Triage Team, JoshStrobl

Subscribers: JoshStrobl

Differential Revision: https://dev.getsol.us/D12150