graphics/gimp3-app: update to 3.0.6 release (+)
Micro releases like 3.0.6 are focused on fixing bugs and regressions.
Many of these have already been announced in development 3.1.2 and 3.1.4 news posts.
Release notes: https://www.gimp.org/news/2025/10/06/gimp-3-0-6-released/