graphics/openimageio: update to 2.3.12.0 release (+)

Changelog: https://github.com/OpenImageIO/oiio/releases/tag/v2.3.12.0

While here, drop unneeded dependency on openjpeg15 [1]

PR: 262016 [1]
Approved by: maintainer
Sponsored by: Netzkommune GmbH